cc/trees/layer_tree_host_impl.cc

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/trees/layer_tree_host_impl.h"
   6
   7 #include <algorithm>
   8 #include <limits>
   9
  10 #include "base/basictypes.h"
  11 #include "base/containers/hash_tables.h"
  12 #include "base/debug/trace_event_argument.h"
  13 #include "base/json/json_writer.h"
  14 #include "base/metrics/histogram.h"
  15 #include "base/stl_util.h"
  16 #include "base/strings/stringprintf.h"
  17 #include "cc/animation/animation_id_provider.h"
  18 #include "cc/animation/scroll_offset_animation_curve.h"
  19 #include "cc/animation/scrollbar_animation_controller.h"
  20 #include "cc/animation/timing_function.h"
  21 #include "cc/base/latency_info_swap_promise_monitor.h"
  22 #include "cc/base/math_util.h"
  23 #include "cc/base/util.h"
  24 #include "cc/debug/benchmark_instrumentation.h"
  25 #include "cc/debug/debug_rect_history.h"
  26 #include "cc/debug/devtools_instrumentation.h"
  27 #include "cc/debug/frame_rate_counter.h"
  28 #include "cc/debug/paint_time_counter.h"
  29 #include "cc/debug/rendering_stats_instrumentation.h"
  30 #include "cc/debug/traced_value.h"
  31 #include "cc/input/page_scale_animation.h"
  32 #include "cc/input/top_controls_manager.h"
  33 #include "cc/layers/append_quads_data.h"
  34 #include "cc/layers/heads_up_display_layer_impl.h"
  35 #include "cc/layers/layer_impl.h"
  36 #include "cc/layers/layer_iterator.h"
  37 #include "cc/layers/painted_scrollbar_layer_impl.h"
  38 #include "cc/layers/render_surface_impl.h"
  39 #include "cc/layers/scrollbar_layer_impl_base.h"
  40 #include "cc/output/compositor_frame_metadata.h"
  41 #include "cc/output/copy_output_request.h"
  42 #include "cc/output/delegating_renderer.h"
  43 #include "cc/output/gl_renderer.h"
  44 #include "cc/output/software_renderer.h"
  45 #include "cc/quads/render_pass_draw_quad.h"
  46 #include "cc/quads/shared_quad_state.h"
  47 #include "cc/quads/solid_color_draw_quad.h"
  48 #include "cc/quads/texture_draw_quad.h"
  49 #include "cc/resources/eviction_tile_priority_queue.h"
  50 #include "cc/resources/gpu_raster_worker_pool.h"
  51 #include "cc/resources/image_copy_raster_worker_pool.h"
  52 #include "cc/resources/image_raster_worker_pool.h"
  53 #include "cc/resources/memory_history.h"
  54 #include "cc/resources/picture_layer_tiling.h"
  55 #include "cc/resources/pixel_buffer_raster_worker_pool.h"
  56 #include "cc/resources/prioritized_resource_manager.h"
  57 #include "cc/resources/raster_tile_priority_queue.h"
  58 #include "cc/resources/raster_worker_pool.h"
  59 #include "cc/resources/resource_pool.h"
  60 #include "cc/resources/texture_mailbox_deleter.h"
  61 #include "cc/resources/ui_resource_bitmap.h"
  62 #include "cc/scheduler/delay_based_time_source.h"
  63 #include "cc/trees/damage_tracker.h"
  64 #include "cc/trees/layer_tree_host.h"
  65 #include "cc/trees/layer_tree_host_common.h"
  66 #include "cc/trees/layer_tree_impl.h"
  67 #include "cc/trees/occlusion_tracker.h"
  68 #include "cc/trees/single_thread_proxy.h"
  69 #include "cc/trees/tree_synchronizer.h"
  70 #include "gpu/command_buffer/client/gles2_interface.h"
  71 #include "gpu/GLES2/gl2extchromium.h"
  72 #include "ui/gfx/frame_time.h"
  73 #include "ui/gfx/geometry/rect_conversions.h"
  74 #include "ui/gfx/size_conversions.h"
  75 #include "ui/gfx/vector2d_conversions.h"
  76
  77 namespace {
  78
  79 void DidVisibilityChange(cc::LayerTreeHostImpl* id, bool visible) {
  80   if (visible) {
  81     TRACE_EVENT_ASYNC_BEGIN1("webkit",
  82                              "LayerTreeHostImpl::SetVisible",
  83                              id,
  84                              "LayerTreeHostImpl",
  85                              id);
  86     return;
  87   }
  88
  89   TRACE_EVENT_ASYNC_END0("webkit", "LayerTreeHostImpl::SetVisible", id);
  90 }
  91
  92 size_t GetMaxTransferBufferUsageBytes(cc::ContextProvider* context_provider,
  93                                       double refresh_rate) {
  94   // Software compositing should not use this value in production. Just use a
  95   // default value when testing uploads with the software compositor.
  96   if (!context_provider)
  97     return std::numeric_limits<size_t>::max();
  98
  99   // We want to make sure the default transfer buffer size is equal to the
 100   // amount of data that can be uploaded by the compositor to avoid stalling
 101   // the pipeline.
 102   // For reference Chromebook Pixel can upload 1MB in about 0.5ms.
 103   const size_t kMaxBytesUploadedPerMs = 1024 * 1024 * 2;
 104
 105   // We need to upload at least enough work to keep the GPU process busy until
 106   // the next time it can handle a request to start more uploads from the
 107   // compositor. We assume that it will pick up any sent upload requests within
 108   // the time of a vsync, since the browser will want to swap a frame within
 109   // that time interval, and then uploads should have a chance to be processed.
 110   size_t ms_per_frame = std::floor(1000.0 / refresh_rate);
 111   size_t max_transfer_buffer_usage_bytes =
 112       ms_per_frame * kMaxBytesUploadedPerMs;
 113
 114   // The context may request a lower limit based on the device capabilities.
 115   return std::min(
 116       context_provider->ContextCapabilities().max_transfer_buffer_usage_bytes,
 117       max_transfer_buffer_usage_bytes);
 118 }
 119
 120 unsigned GetMapImageTextureTarget(cc::ContextProvider* context_provider) {
 121   if (!context_provider)
 122     return GL_TEXTURE_2D;
 123
 124   if (context_provider->ContextCapabilities().gpu.egl_image_external)
 125     return GL_TEXTURE_EXTERNAL_OES;
 126   if (context_provider->ContextCapabilities().gpu.texture_rectangle)
 127     return GL_TEXTURE_RECTANGLE_ARB;
 128
 129   return GL_TEXTURE_2D;
 130 }
 131
 132 }  // namespace
 133
 134 namespace cc {
 135
 136 class LayerTreeHostImplTimeSourceAdapter : public TimeSourceClient {
 137  public:
 138   static scoped_ptr<LayerTreeHostImplTimeSourceAdapter> Create(
 139       LayerTreeHostImpl* layer_tree_host_impl,
 140       scoped_refptr<DelayBasedTimeSource> time_source) {
 141     return make_scoped_ptr(
 142         new LayerTreeHostImplTimeSourceAdapter(layer_tree_host_impl,
 143                                                time_source));
 144   }
 145   virtual ~LayerTreeHostImplTimeSourceAdapter() {
 146     time_source_->SetClient(NULL);
 147     time_source_->SetActive(false);
 148   }
 149
 150   virtual void OnTimerTick() OVERRIDE {
 151     // In single threaded mode we attempt to simulate changing the current
 152     // thread by maintaining a fake thread id. When we switch from one
 153     // thread to another, we construct DebugScopedSetXXXThread objects that
 154     // update the thread id. This lets DCHECKS that ensure we're on the
 155     // right thread to work correctly in single threaded mode. The problem
 156     // here is that the timer tasks are run via the message loop, and when
 157     // they run, we've had no chance to construct a DebugScopedSetXXXThread
 158     // object. The result is that we report that we're running on the main
 159     // thread. In multi-threaded mode, this timer is run on the compositor
 160     // thread, so to keep this consistent in single-threaded mode, we'll
 161     // construct a DebugScopedSetImplThread object. There is no need to do
 162     // this in multi-threaded mode since the real thread id's will be
 163     // correct. In fact, setting fake thread id's interferes with the real
 164     // thread id's and causes breakage.
 165     scoped_ptr<DebugScopedSetImplThread> set_impl_thread;
 166     if (!layer_tree_host_impl_->proxy()->HasImplThread()) {
 167       set_impl_thread.reset(
 168           new DebugScopedSetImplThread(layer_tree_host_impl_->proxy()));
 169     }
 170
 171     layer_tree_host_impl_->Animate(
 172         layer_tree_host_impl_->CurrentBeginFrameArgs().frame_time);
 173     layer_tree_host_impl_->UpdateBackgroundAnimateTicking(true);
 174     bool start_ready_animations = true;
 175     layer_tree_host_impl_->UpdateAnimationState(start_ready_animations);
 176
 177     if (layer_tree_host_impl_->pending_tree()) {
 178       layer_tree_host_impl_->pending_tree()->UpdateDrawProperties();
 179       layer_tree_host_impl_->ManageTiles();
 180     }
 181
 182     layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();
 183   }
 184
 185   void SetActive(bool active) {
 186     if (active != time_source_->Active())
 187       time_source_->SetActive(active);
 188   }
 189
 190   bool Active() const { return time_source_->Active(); }
 191
 192  private:
 193   LayerTreeHostImplTimeSourceAdapter(
 194       LayerTreeHostImpl* layer_tree_host_impl,
 195       scoped_refptr<DelayBasedTimeSource> time_source)
 196       : layer_tree_host_impl_(layer_tree_host_impl),
 197         time_source_(time_source) {
 198     time_source_->SetClient(this);
 199   }
 200
 201   LayerTreeHostImpl* layer_tree_host_impl_;
 202   scoped_refptr<DelayBasedTimeSource> time_source_;
 203
 204   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImplTimeSourceAdapter);
 205 };
 206
 207 LayerTreeHostImpl::FrameData::FrameData()
 208     : contains_incomplete_tile(false), has_no_damage(false) {}
 209
 210 LayerTreeHostImpl::FrameData::~FrameData() {}
 211
 212 scoped_ptr<LayerTreeHostImpl> LayerTreeHostImpl::Create(
 213     const LayerTreeSettings& settings,
 214     LayerTreeHostImplClient* client,
 215     Proxy* proxy,
 216     RenderingStatsInstrumentation* rendering_stats_instrumentation,
 217     SharedBitmapManager* manager,
 218     int id) {
 219   return make_scoped_ptr(new LayerTreeHostImpl(
 220       settings, client, proxy, rendering_stats_instrumentation, manager, id));
 221 }
 222
 223 LayerTreeHostImpl::LayerTreeHostImpl(
 224     const LayerTreeSettings& settings,
 225     LayerTreeHostImplClient* client,
 226     Proxy* proxy,
 227     RenderingStatsInstrumentation* rendering_stats_instrumentation,
 228     SharedBitmapManager* manager,
 229     int id)
 230     : client_(client),
 231       proxy_(proxy),
 232       use_gpu_rasterization_(false),
 233       input_handler_client_(NULL),
 234       did_lock_scrolling_layer_(false),
 235       should_bubble_scrolls_(false),
 236       wheel_scrolling_(false),
 237       scroll_affects_scroll_handler_(false),
 238       scroll_layer_id_when_mouse_over_scrollbar_(0),
 239       tile_priorities_dirty_(false),
 240       root_layer_scroll_offset_delegate_(NULL),
 241       settings_(settings),
 242       visible_(true),
 243       cached_managed_memory_policy_(
 244           PrioritizedResourceManager::DefaultMemoryAllocationLimit(),
 245           gpu::MemoryAllocation::CUTOFF_ALLOW_EVERYTHING,
 246           ManagedMemoryPolicy::kDefaultNumResourcesLimit),
 247       pinch_gesture_active_(false),
 248       pinch_gesture_end_should_clear_scrolling_layer_(false),
 249       fps_counter_(FrameRateCounter::Create(proxy_->HasImplThread())),
 250       paint_time_counter_(PaintTimeCounter::Create()),
 251       memory_history_(MemoryHistory::Create()),
 252       debug_rect_history_(DebugRectHistory::Create()),
 253       texture_mailbox_deleter_(new TextureMailboxDeleter(
 254           proxy_->HasImplThread() ? proxy_->ImplThreadTaskRunner()
 255                                   : proxy_->MainThreadTaskRunner())),
 256       max_memory_needed_bytes_(0),
 257       zero_budget_(false),
 258       device_scale_factor_(1.f),
 259       overhang_ui_resource_id_(0),
 260       top_controls_layout_height_(0.f),
 261       resourceless_software_draw_(false),
 262       begin_impl_frame_interval_(BeginFrameArgs::DefaultInterval()),
 263       animation_registrar_(AnimationRegistrar::Create()),
 264       rendering_stats_instrumentation_(rendering_stats_instrumentation),
 265       micro_benchmark_controller_(this),
 266       need_to_update_visible_tiles_before_draw_(false),
 267       shared_bitmap_manager_(manager),
 268       id_(id),
 269       transfer_buffer_memory_limit_(0u) {
 270   DCHECK(proxy_->IsImplThread());
 271   DidVisibilityChange(this, visible_);
 272   animation_registrar_->set_supports_scroll_animations(
 273       proxy_->SupportsImplScrolling());
 274
 275   SetDebugState(settings.initial_debug_state);
 276
 277   if (settings.calculate_top_controls_position) {
 278     top_controls_manager_ =
 279         TopControlsManager::Create(this,
 280                                    settings.top_controls_height,
 281                                    settings.top_controls_show_threshold,
 282                                    settings.top_controls_hide_threshold);
 283   }
 284
 285   SetDebugState(settings.initial_debug_state);
 286
 287   // LTHI always has an active tree.
 288   active_tree_ = LayerTreeImpl::create(this);
 289   TRACE_EVENT_OBJECT_CREATED_WITH_ID(
 290       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 291 }
 292
 293 LayerTreeHostImpl::~LayerTreeHostImpl() {
 294   DCHECK(proxy_->IsImplThread());
 295   TRACE_EVENT0("cc", "LayerTreeHostImpl::~LayerTreeHostImpl()");
 296   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
 297       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 298
 299   if (input_handler_client_) {
 300     input_handler_client_->WillShutdown();
 301     input_handler_client_ = NULL;
 302   }
 303
 304   // The layer trees must be destroyed before the layer tree host. We've
 305   // made a contract with our animation controllers that the registrar
 306   // will outlive them, and we must make good.
 307   if (recycle_tree_)
 308     recycle_tree_->Shutdown();
 309   if (pending_tree_)
 310     pending_tree_->Shutdown();
 311   active_tree_->Shutdown();
 312   recycle_tree_.reset();
 313   pending_tree_.reset();
 314   active_tree_.reset();
 315   DestroyTileManager();
 316 }
 317
 318 void LayerTreeHostImpl::BeginMainFrameAborted(bool did_handle) {
 319   // If the begin frame data was handled, then scroll and scale set was applied
 320   // by the main thread, so the active tree needs to be updated as if these sent
 321   // values were applied and committed.
 322   if (did_handle) {
 323     active_tree_->ApplySentScrollAndScaleDeltasFromAbortedCommit();
 324     active_tree_->ResetContentsTexturesPurged();
 325   }
 326 }
 327
 328 void LayerTreeHostImpl::BeginCommit() {
 329   TRACE_EVENT0("cc", "LayerTreeHostImpl::BeginCommit");
 330
 331   if (UsePendingTreeForSync())
 332     CreatePendingTree();
 333 }
 334
 335 void LayerTreeHostImpl::CommitComplete() {
 336   TRACE_EVENT0("cc", "LayerTreeHostImpl::CommitComplete");
 337
 338   if (pending_tree_)
 339     pending_tree_->ApplyScrollDeltasSinceBeginMainFrame();
 340   sync_tree()->set_needs_update_draw_properties();
 341
 342   if (settings_.impl_side_painting) {
 343     // Impl-side painting needs an update immediately post-commit to have the
 344     // opportunity to create tilings.  Other paths can call UpdateDrawProperties
 345     // more lazily when needed prior to drawing.
 346     sync_tree()->UpdateDrawProperties();
 347     // Start working on newly created tiles immediately if needed.
 348     if (tile_manager_ && tile_priorities_dirty_)
 349       ManageTiles();
 350     else
 351       NotifyReadyToActivate();
 352   } else {
 353     // If we're not in impl-side painting, the tree is immediately considered
 354     // active.
 355     ActivateSyncTree();
 356   }
 357
 358   micro_benchmark_controller_.DidCompleteCommit();
 359 }
 360
 361 bool LayerTreeHostImpl::CanDraw() const {
 362   // Note: If you are changing this function or any other function that might
 363   // affect the result of CanDraw, make sure to call
 364   // client_->OnCanDrawStateChanged in the proper places and update the
 365   // NotifyIfCanDrawChanged test.
 366
 367   if (!renderer_) {
 368     TRACE_EVENT_INSTANT0("cc", "LayerTreeHostImpl::CanDraw no renderer",
 369                          TRACE_EVENT_SCOPE_THREAD);
 370     return false;
 371   }
 372
 373   // Must have an OutputSurface if |renderer_| is not NULL.
 374   DCHECK(output_surface_);
 375
 376   // TODO(boliu): Make draws without root_layer work and move this below
 377   // draw_and_swap_full_viewport_every_frame check. Tracked in crbug.com/264967.
 378   if (!active_tree_->root_layer()) {
 379     TRACE_EVENT_INSTANT0("cc", "LayerTreeHostImpl::CanDraw no root layer",
 380                          TRACE_EVENT_SCOPE_THREAD);
 381     return false;
 382   }
 383
 384   if (output_surface_->capabilities().draw_and_swap_full_viewport_every_frame)
 385     return true;
 386
 387   if (DrawViewportSize().IsEmpty()) {
 388     TRACE_EVENT_INSTANT0("cc", "LayerTreeHostImpl::CanDraw empty viewport",
 389                          TRACE_EVENT_SCOPE_THREAD);
 390     return false;
 391   }
 392   if (active_tree_->ViewportSizeInvalid()) {
 393     TRACE_EVENT_INSTANT0(
 394         "cc", "LayerTreeHostImpl::CanDraw viewport size recently changed",
 395         TRACE_EVENT_SCOPE_THREAD);
 396     return false;
 397   }
 398   if (active_tree_->ContentsTexturesPurged()) {
 399     TRACE_EVENT_INSTANT0(
 400         "cc", "LayerTreeHostImpl::CanDraw contents textures purged",
 401         TRACE_EVENT_SCOPE_THREAD);
 402     return false;
 403   }
 404   if (EvictedUIResourcesExist()) {
 405     TRACE_EVENT_INSTANT0(
 406         "cc", "LayerTreeHostImpl::CanDraw UI resources evicted not recreated",
 407         TRACE_EVENT_SCOPE_THREAD);
 408     return false;
 409   }
 410   return true;
 411 }
 412
 413 void LayerTreeHostImpl::Animate(base::TimeTicks monotonic_time) {
 414   if (input_handler_client_)
 415     input_handler_client_->Animate(monotonic_time);
 416   AnimatePageScale(monotonic_time);
 417   AnimateLayers(monotonic_time);
 418   AnimateScrollbars(monotonic_time);
 419   AnimateTopControls(monotonic_time);
 420 }
 421
 422 void LayerTreeHostImpl::ManageTiles() {
 423   if (!tile_manager_)
 424     return;
 425   if (!tile_priorities_dirty_)
 426     return;
 427
 428   tile_priorities_dirty_ = false;
 429   tile_manager_->ManageTiles(global_tile_state_);
 430
 431   client_->DidManageTiles();
 432 }
 433
 434 void LayerTreeHostImpl::StartPageScaleAnimation(
 435     const gfx::Vector2d& target_offset,
 436     bool anchor_point,
 437     float page_scale,
 438     base::TimeDelta duration) {
 439   if (!InnerViewportScrollLayer())
 440     return;
 441
 442   gfx::Vector2dF scroll_total = active_tree_->TotalScrollOffset();
 443   gfx::SizeF scaled_scrollable_size = active_tree_->ScrollableSize();
 444   gfx::SizeF viewport_size =
 445       active_tree_->InnerViewportContainerLayer()->bounds();
 446
 447   // Easing constants experimentally determined.
 448   scoped_ptr<TimingFunction> timing_function =
 449       CubicBezierTimingFunction::Create(.8, 0, .3, .9).PassAs<TimingFunction>();
 450
 451   page_scale_animation_ =
 452       PageScaleAnimation::Create(scroll_total,
 453                                  active_tree_->total_page_scale_factor(),
 454                                  viewport_size,
 455                                  scaled_scrollable_size,
 456                                  timing_function.Pass());
 457
 458   if (anchor_point) {
 459     gfx::Vector2dF anchor(target_offset);
 460     page_scale_animation_->ZoomWithAnchor(anchor,
 461                                           page_scale,
 462                                           duration.InSecondsF());
 463   } else {
 464     gfx::Vector2dF scaled_target_offset = target_offset;
 465     page_scale_animation_->ZoomTo(scaled_target_offset,
 466                                   page_scale,
 467                                   duration.InSecondsF());
 468   }
 469
 470   SetNeedsAnimate();
 471   client_->SetNeedsCommitOnImplThread();
 472   client_->RenewTreePriority();
 473 }
 474
 475 bool LayerTreeHostImpl::IsCurrentlyScrollingLayerAt(
 476     const gfx::Point& viewport_point,
 477     InputHandler::ScrollInputType type) {
 478   if (!CurrentlyScrollingLayer())
 479     return false;
 480
 481   gfx::PointF device_viewport_point =
 482       gfx::ScalePoint(viewport_point, device_scale_factor_);
 483
 484   LayerImpl* layer_impl =
 485       active_tree_->FindLayerThatIsHitByPoint(device_viewport_point);
 486
 487   bool scroll_on_main_thread = false;
 488   LayerImpl* scrolling_layer_impl = FindScrollLayerForDeviceViewportPoint(
 489       device_viewport_point, type, layer_impl, &scroll_on_main_thread, NULL);
 490   return CurrentlyScrollingLayer() == scrolling_layer_impl;
 491 }
 492
 493 bool LayerTreeHostImpl::HaveTouchEventHandlersAt(
 494     const gfx::Point& viewport_point) {
 495
 496   gfx::PointF device_viewport_point =
 497       gfx::ScalePoint(viewport_point, device_scale_factor_);
 498
 499   LayerImpl* layer_impl =
 500       active_tree_->FindLayerThatIsHitByPointInTouchHandlerRegion(
 501           device_viewport_point);
 502
 503   return layer_impl != NULL;
 504 }
 505
 506 scoped_ptr<SwapPromiseMonitor>
 507 LayerTreeHostImpl::CreateLatencyInfoSwapPromiseMonitor(
 508     ui::LatencyInfo* latency) {
 509   return scoped_ptr<SwapPromiseMonitor>(
 510       new LatencyInfoSwapPromiseMonitor(latency, NULL, this));
 511 }
 512
 513 void LayerTreeHostImpl::QueueSwapPromiseForMainThreadScrollUpdate(
 514     scoped_ptr<SwapPromise> swap_promise) {
 515   swap_promises_for_main_thread_scroll_update_.push_back(swap_promise.Pass());
 516 }
 517
 518 void LayerTreeHostImpl::TrackDamageForAllSurfaces(
 519     LayerImpl* root_draw_layer,
 520     const LayerImplList& render_surface_layer_list) {
 521   // For now, we use damage tracking to compute a global scissor. To do this, we
 522   // must compute all damage tracking before drawing anything, so that we know
 523   // the root damage rect. The root damage rect is then used to scissor each
 524   // surface.
 525
 526   for (int surface_index = render_surface_layer_list.size() - 1;
 527        surface_index >= 0;
 528        --surface_index) {
 529     LayerImpl* render_surface_layer = render_surface_layer_list[surface_index];
 530     RenderSurfaceImpl* render_surface = render_surface_layer->render_surface();
 531     DCHECK(render_surface);
 532     render_surface->damage_tracker()->UpdateDamageTrackingState(
 533         render_surface->layer_list(),
 534         render_surface_layer->id(),
 535         render_surface->SurfacePropertyChangedOnlyFromDescendant(),
 536         render_surface->content_rect(),
 537         render_surface_layer->mask_layer(),
 538         render_surface_layer->filters());
 539   }
 540 }
 541
 542 void LayerTreeHostImpl::FrameData::AsValueInto(
 543     base::debug::TracedValue* value) const {
 544   value->SetBoolean("contains_incomplete_tile", contains_incomplete_tile);
 545   value->SetBoolean("has_no_damage", has_no_damage);
 546
 547   // Quad data can be quite large, so only dump render passes if we select
 548   // cc.debug.quads.
 549   bool quads_enabled;
 550   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
 551       TRACE_DISABLED_BY_DEFAULT("cc.debug.quads"), &quads_enabled);
 552   if (quads_enabled) {
 553     value->BeginArray("render_passes");
 554     for (size_t i = 0; i < render_passes.size(); ++i) {
 555       value->BeginDictionary();
 556       render_passes[i]->AsValueInto(value);
 557       value->EndDictionary();
 558     }
 559     value->EndArray();
 560   }
 561 }
 562
 563 void LayerTreeHostImpl::FrameData::AppendRenderPass(
 564     scoped_ptr<RenderPass> render_pass) {
 565   render_passes_by_id[render_pass->id] = render_pass.get();
 566   render_passes.push_back(render_pass.Pass());
 567 }
 568
 569 DrawMode LayerTreeHostImpl::GetDrawMode() const {
 570   if (resourceless_software_draw_) {
 571     return DRAW_MODE_RESOURCELESS_SOFTWARE;
 572   } else if (output_surface_->context_provider()) {
 573     return DRAW_MODE_HARDWARE;
 574   } else {
 575     DCHECK_EQ(!output_surface_->software_device(),
 576               output_surface_->capabilities().delegated_rendering &&
 577                   !output_surface_->capabilities().deferred_gl_initialization)
 578         << output_surface_->capabilities().delegated_rendering << " "
 579         << output_surface_->capabilities().deferred_gl_initialization;
 580     return DRAW_MODE_SOFTWARE;
 581   }
 582 }
 583
 584 static void AppendQuadsForLayer(
 585     RenderPass* target_render_pass,
 586     LayerImpl* layer,
 587     const OcclusionTracker<LayerImpl>& occlusion_tracker,
 588     AppendQuadsData* append_quads_data) {
 589   layer->AppendQuads(target_render_pass, occlusion_tracker, append_quads_data);
 590 }
 591
 592 static void AppendQuadsForRenderSurfaceLayer(
 593     RenderPass* target_render_pass,
 594     LayerImpl* layer,
 595     const RenderPass* contributing_render_pass,
 596     const OcclusionTracker<LayerImpl>& occlusion_tracker,
 597     AppendQuadsData* append_quads_data) {
 598   bool is_replica = false;
 599   layer->render_surface()->AppendQuads(target_render_pass,
 600                                        occlusion_tracker,
 601                                        append_quads_data,
 602                                        is_replica,
 603                                        contributing_render_pass->id);
 604
 605   // Add replica after the surface so that it appears below the surface.
 606   if (layer->has_replica()) {
 607     is_replica = true;
 608     layer->render_surface()->AppendQuads(target_render_pass,
 609                                          occlusion_tracker,
 610                                          append_quads_data,
 611                                          is_replica,
 612                                          contributing_render_pass->id);
 613   }
 614 }
 615
 616 static void AppendQuadsToFillScreen(
 617     ResourceProvider::ResourceId overhang_resource_id,
 618     const gfx::SizeF& overhang_resource_scaled_size,
 619     const gfx::Rect& root_scroll_layer_rect,
 620     RenderPass* target_render_pass,
 621     LayerImpl* root_layer,
 622     SkColor screen_background_color,
 623     const OcclusionTracker<LayerImpl>& occlusion_tracker) {
 624   if (!root_layer || !SkColorGetA(screen_background_color))
 625     return;
 626
 627   Region fill_region = occlusion_tracker.ComputeVisibleRegionInScreen();
 628   if (fill_region.IsEmpty())
 629     return;
 630
 631   // Divide the fill region into the part to be filled with the overhang
 632   // resource and the part to be filled with the background color.
 633   Region screen_background_color_region = fill_region;
 634   Region overhang_region;
 635   if (overhang_resource_id) {
 636     overhang_region = fill_region;
 637     overhang_region.Subtract(root_scroll_layer_rect);
 638     screen_background_color_region.Intersect(root_scroll_layer_rect);
 639   }
 640
 641   // Manually create the quad state for the gutter quads, as the root layer
 642   // doesn't have any bounds and so can't generate this itself.
 643   // TODO(danakj): Make the gutter quads generated by the solid color layer
 644   // (make it smarter about generating quads to fill unoccluded areas).
 645
 646   gfx::Rect root_target_rect = root_layer->render_surface()->content_rect();
 647   float opacity = 1.f;
 648   int sorting_context_id = 0;
 649   SharedQuadState* shared_quad_state =
 650       target_render_pass->CreateAndAppendSharedQuadState();
 651   shared_quad_state->SetAll(gfx::Transform(),
 652                             root_target_rect.size(),
 653                             root_target_rect,
 654                             root_target_rect,
 655                             false,
 656                             opacity,
 657                             SkXfermode::kSrcOver_Mode,
 658                             sorting_context_id);
 659
 660   for (Region::Iterator fill_rects(screen_background_color_region);
 661        fill_rects.has_rect();
 662        fill_rects.next()) {
 663     gfx::Rect screen_space_rect = fill_rects.rect();
 664     gfx::Rect visible_screen_space_rect = screen_space_rect;
 665     // Skip the quad culler and just append the quads directly to avoid
 666     // occlusion checks.
 667     SolidColorDrawQuad* quad =
 668         target_render_pass->CreateAndAppendDrawQuad<SolidColorDrawQuad>();
 669     quad->SetNew(shared_quad_state,
 670                  screen_space_rect,
 671                  visible_screen_space_rect,
 672                  screen_background_color,
 673                  false);
 674   }
 675   for (Region::Iterator fill_rects(overhang_region);
 676        fill_rects.has_rect();
 677        fill_rects.next()) {
 678     DCHECK(overhang_resource_id);
 679     gfx::Rect screen_space_rect = fill_rects.rect();
 680     gfx::Rect opaque_screen_space_rect = screen_space_rect;
 681     gfx::Rect visible_screen_space_rect = screen_space_rect;
 682     TextureDrawQuad* tex_quad =
 683         target_render_pass->CreateAndAppendDrawQuad<TextureDrawQuad>();
 684     const float vertex_opacity[4] = {1.f, 1.f, 1.f, 1.f};
 685     tex_quad->SetNew(
 686         shared_quad_state,
 687         screen_space_rect,
 688         opaque_screen_space_rect,
 689         visible_screen_space_rect,
 690         overhang_resource_id,
 691         false,
 692         gfx::PointF(
 693             screen_space_rect.x() / overhang_resource_scaled_size.width(),
 694             screen_space_rect.y() / overhang_resource_scaled_size.height()),
 695         gfx::PointF(
 696             screen_space_rect.right() / overhang_resource_scaled_size.width(),
 697             screen_space_rect.bottom() /
 698                 overhang_resource_scaled_size.height()),
 699         screen_background_color,
 700         vertex_opacity,
 701         false);
 702   }
 703 }
 704
 705 DrawResult LayerTreeHostImpl::CalculateRenderPasses(
 706     FrameData* frame) {
 707   DCHECK(frame->render_passes.empty());
 708   DCHECK(CanDraw());
 709   DCHECK(active_tree_->root_layer());
 710
 711   TrackDamageForAllSurfaces(active_tree_->root_layer(),
 712                             *frame->render_surface_layer_list);
 713
 714   // If the root render surface has no visible damage, then don't generate a
 715   // frame at all.
 716   RenderSurfaceImpl* root_surface =
 717       active_tree_->root_layer()->render_surface();
 718   bool root_surface_has_no_visible_damage =
 719       !root_surface->damage_tracker()->current_damage_rect().Intersects(
 720           root_surface->content_rect());
 721   bool root_surface_has_contributing_layers =
 722       !root_surface->layer_list().empty();
 723   bool hud_wants_to_draw_ = active_tree_->hud_layer() &&
 724                             active_tree_->hud_layer()->IsAnimatingHUDContents();
 725   if (root_surface_has_contributing_layers &&
 726       root_surface_has_no_visible_damage &&
 727       active_tree_->LayersWithCopyOutputRequest().empty() &&
 728       !hud_wants_to_draw_) {
 729     TRACE_EVENT0("cc",
 730                  "LayerTreeHostImpl::CalculateRenderPasses::EmptyDamageRect");
 731     frame->has_no_damage = true;
 732     DCHECK(!output_surface_->capabilities()
 733                .draw_and_swap_full_viewport_every_frame);
 734     return DRAW_SUCCESS;
 735   }
 736
 737   TRACE_EVENT1("cc",
 738                "LayerTreeHostImpl::CalculateRenderPasses",
 739                "render_surface_layer_list.size()",
 740                static_cast<uint64>(frame->render_surface_layer_list->size()));
 741
 742   // Create the render passes in dependency order.
 743   for (int surface_index = frame->render_surface_layer_list->size() - 1;
 744        surface_index >= 0;
 745        --surface_index) {
 746     LayerImpl* render_surface_layer =
 747         (*frame->render_surface_layer_list)[surface_index];
 748     RenderSurfaceImpl* render_surface = render_surface_layer->render_surface();
 749
 750     bool should_draw_into_render_pass =
 751         render_surface_layer->parent() == NULL ||
 752         render_surface->contributes_to_drawn_surface() ||
 753         render_surface_layer->HasCopyRequest();
 754     if (should_draw_into_render_pass)
 755       render_surface_layer->render_surface()->AppendRenderPasses(frame);
 756   }
 757
 758   // When we are displaying the HUD, change the root damage rect to cover the
 759   // entire root surface. This will disable partial-swap/scissor optimizations
 760   // that would prevent the HUD from updating, since the HUD does not cause
 761   // damage itself, to prevent it from messing with damage visualizations. Since
 762   // damage visualizations are done off the LayerImpls and RenderSurfaceImpls,
 763   // changing the RenderPass does not affect them.
 764   if (active_tree_->hud_layer()) {
 765     RenderPass* root_pass = frame->render_passes.back();
 766     root_pass->damage_rect = root_pass->output_rect;
 767   }
 768
 769   OcclusionTracker<LayerImpl> occlusion_tracker(
 770       active_tree_->root_layer()->render_surface()->content_rect());
 771   occlusion_tracker.set_minimum_tracking_size(
 772       settings_.minimum_occlusion_tracking_size);
 773
 774   if (debug_state_.show_occluding_rects) {
 775     occlusion_tracker.set_occluding_screen_space_rects_container(
 776         &frame->occluding_screen_space_rects);
 777   }
 778   if (debug_state_.show_non_occluding_rects) {
 779     occlusion_tracker.set_non_occluding_screen_space_rects_container(
 780         &frame->non_occluding_screen_space_rects);
 781   }
 782
 783   // Add quads to the Render passes in front-to-back order to allow for testing
 784   // occlusion and performing culling during the tree walk.
 785   typedef LayerIterator<LayerImpl> LayerIteratorType;
 786
 787   // Typically when we are missing a texture and use a checkerboard quad, we
 788   // still draw the frame. However when the layer being checkerboarded is moving
 789   // due to an impl-animation, we drop the frame to avoid flashing due to the
 790   // texture suddenly appearing in the future.
 791   DrawResult draw_result = DRAW_SUCCESS;
 792   // When we have a copy request for a layer, we need to draw no matter
 793   // what, as the layer may disappear after this frame.
 794   bool have_copy_request = false;
 795
 796   int layers_drawn = 0;
 797
 798   const DrawMode draw_mode = GetDrawMode();
 799
 800   int num_missing_tiles = 0;
 801   int num_incomplete_tiles = 0;
 802
 803   LayerIteratorType end =
 804       LayerIteratorType::End(frame->render_surface_layer_list);
 805   for (LayerIteratorType it =
 806            LayerIteratorType::Begin(frame->render_surface_layer_list);
 807        it != end;
 808        ++it) {
 809     RenderPassId target_render_pass_id =
 810         it.target_render_surface_layer()->render_surface()->GetRenderPassId();
 811     RenderPass* target_render_pass =
 812         frame->render_passes_by_id[target_render_pass_id];
 813
 814     occlusion_tracker.EnterLayer(it);
 815
 816     AppendQuadsData append_quads_data(target_render_pass_id);
 817
 818     if (it.represents_target_render_surface()) {
 819       if (it->HasCopyRequest()) {
 820         have_copy_request = true;
 821         it->TakeCopyRequestsAndTransformToTarget(
 822             &target_render_pass->copy_requests);
 823       }
 824     } else if (it.represents_contributing_render_surface() &&
 825                it->render_surface()->contributes_to_drawn_surface()) {
 826       RenderPassId contributing_render_pass_id =
 827           it->render_surface()->GetRenderPassId();
 828       RenderPass* contributing_render_pass =
 829           frame->render_passes_by_id[contributing_render_pass_id];
 830       AppendQuadsForRenderSurfaceLayer(target_render_pass,
 831                                        *it,
 832                                        contributing_render_pass,
 833                                        occlusion_tracker,
 834                                        &append_quads_data);
 835     } else if (it.represents_itself() &&
 836                !it->visible_content_rect().IsEmpty()) {
 837       bool occluded = occlusion_tracker.Occluded(it->render_target(),
 838                                                  it->visible_content_rect(),
 839                                                  it->draw_transform());
 840       if (!occluded && it->WillDraw(draw_mode, resource_provider_.get())) {
 841         DCHECK_EQ(active_tree_, it->layer_tree_impl());
 842
 843         frame->will_draw_layers.push_back(*it);
 844
 845         if (it->HasContributingDelegatedRenderPasses()) {
 846           RenderPassId contributing_render_pass_id =
 847               it->FirstContributingRenderPassId();
 848           while (frame->render_passes_by_id.find(contributing_render_pass_id) !=
 849                  frame->render_passes_by_id.end()) {
 850             RenderPass* render_pass =
 851                 frame->render_passes_by_id[contributing_render_pass_id];
 852
 853             AppendQuadsData append_quads_data(render_pass->id);
 854             AppendQuadsForLayer(render_pass,
 855                                 *it,
 856                                 occlusion_tracker,
 857                                 &append_quads_data);
 858
 859             contributing_render_pass_id =
 860                 it->NextContributingRenderPassId(contributing_render_pass_id);
 861           }
 862         }
 863
 864         AppendQuadsForLayer(target_render_pass,
 865                             *it,
 866                             occlusion_tracker,
 867                             &append_quads_data);
 868       }
 869
 870       ++layers_drawn;
 871     }
 872
 873     rendering_stats_instrumentation_->AddVisibleContentArea(
 874         append_quads_data.visible_content_area);
 875     rendering_stats_instrumentation_->AddApproximatedVisibleContentArea(
 876         append_quads_data.approximated_visible_content_area);
 877
 878     num_missing_tiles += append_quads_data.num_missing_tiles;
 879     num_incomplete_tiles += append_quads_data.num_incomplete_tiles;
 880
 881     if (append_quads_data.num_missing_tiles) {
 882       bool layer_has_animating_transform =
 883           it->screen_space_transform_is_animating() ||
 884           it->draw_transform_is_animating();
 885       if (layer_has_animating_transform)
 886         draw_result = DRAW_ABORTED_CHECKERBOARD_ANIMATIONS;
 887     }
 888
 889     if (append_quads_data.num_incomplete_tiles ||
 890         append_quads_data.num_missing_tiles) {
 891       frame->contains_incomplete_tile = true;
 892       if (active_tree()->RequiresHighResToDraw())
 893         draw_result = DRAW_ABORTED_MISSING_HIGH_RES_CONTENT;
 894     }
 895
 896     occlusion_tracker.LeaveLayer(it);
 897   }
 898
 899   if (have_copy_request ||
 900       output_surface_->capabilities().draw_and_swap_full_viewport_every_frame)
 901     draw_result = DRAW_SUCCESS;
 902
 903 #if DCHECK_IS_ON
 904   for (size_t i = 0; i < frame->render_passes.size(); ++i) {
 905     for (size_t j = 0; j < frame->render_passes[i]->quad_list.size(); ++j)
 906       DCHECK(frame->render_passes[i]->quad_list[j]->shared_quad_state);
 907     DCHECK(frame->render_passes_by_id.find(frame->render_passes[i]->id)
 908            != frame->render_passes_by_id.end());
 909   }
 910 #endif
 911   DCHECK(frame->render_passes.back()->output_rect.origin().IsOrigin());
 912
 913   if (!active_tree_->has_transparent_background()) {
 914     frame->render_passes.back()->has_transparent_background = false;
 915     AppendQuadsToFillScreen(
 916         ResourceIdForUIResource(overhang_ui_resource_id_),
 917         gfx::ScaleSize(overhang_ui_resource_size_, device_scale_factor_),
 918         active_tree_->RootScrollLayerDeviceViewportBounds(),
 919         frame->render_passes.back(),
 920         active_tree_->root_layer(),
 921         active_tree_->background_color(),
 922         occlusion_tracker);
 923   }
 924
 925   RemoveRenderPasses(CullRenderPassesWithNoQuads(), frame);
 926   renderer_->DecideRenderPassAllocationsForFrame(frame->render_passes);
 927
 928   // Any copy requests left in the tree are not going to get serviced, and
 929   // should be aborted.
 930   ScopedPtrVector<CopyOutputRequest> requests_to_abort;
 931   while (!active_tree_->LayersWithCopyOutputRequest().empty()) {
 932     LayerImpl* layer = active_tree_->LayersWithCopyOutputRequest().back();
 933     layer->TakeCopyRequestsAndTransformToTarget(&requests_to_abort);
 934   }
 935   for (size_t i = 0; i < requests_to_abort.size(); ++i)
 936     requests_to_abort[i]->SendEmptyResult();
 937
 938   // If we're making a frame to draw, it better have at least one render pass.
 939   DCHECK(!frame->render_passes.empty());
 940
 941   if (active_tree_->has_ever_been_drawn()) {
 942     UMA_HISTOGRAM_COUNTS_100(
 943         "Compositing.RenderPass.AppendQuadData.NumMissingTiles",
 944         num_missing_tiles);
 945     UMA_HISTOGRAM_COUNTS_100(
 946         "Compositing.RenderPass.AppendQuadData.NumIncompleteTiles",
 947         num_incomplete_tiles);
 948   }
 949
 950   // Should only have one render pass in resourceless software mode.
 951   DCHECK(draw_mode != DRAW_MODE_RESOURCELESS_SOFTWARE ||
 952          frame->render_passes.size() == 1u)
 953       << frame->render_passes.size();
 954
 955   return draw_result;
 956 }
 957
 958 void LayerTreeHostImpl::MainThreadHasStoppedFlinging() {
 959   if (input_handler_client_)
 960     input_handler_client_->MainThreadHasStoppedFlinging();
 961 }
 962
 963 void LayerTreeHostImpl::UpdateBackgroundAnimateTicking(
 964     bool should_background_tick) {
 965   DCHECK(proxy_->IsImplThread());
 966   if (should_background_tick)
 967     DCHECK(active_tree_->root_layer());
 968
 969   bool enabled = should_background_tick && needs_animate_layers();
 970
 971   // Lazily create the time_source adapter so that we can vary the interval for
 972   // testing.
 973   if (!time_source_client_adapter_) {
 974     time_source_client_adapter_ = LayerTreeHostImplTimeSourceAdapter::Create(
 975         this,
 976         DelayBasedTimeSource::Create(
 977             LowFrequencyAnimationInterval(),
 978             proxy_->HasImplThread() ? proxy_->ImplThreadTaskRunner()
 979                                     : proxy_->MainThreadTaskRunner()));
 980   }
 981
 982   time_source_client_adapter_->SetActive(enabled);
 983 }
 984
 985 void LayerTreeHostImpl::DidAnimateScrollOffset() {
 986   client_->SetNeedsCommitOnImplThread();
 987   client_->RenewTreePriority();
 988 }
 989
 990 void LayerTreeHostImpl::SetViewportDamage(const gfx::Rect& damage_rect) {
 991   viewport_damage_rect_.Union(damage_rect);
 992 }
 993
 994 static inline RenderPass* FindRenderPassById(
 995     RenderPassId render_pass_id,
 996     const LayerTreeHostImpl::FrameData& frame) {
 997   RenderPassIdHashMap::const_iterator it =
 998       frame.render_passes_by_id.find(render_pass_id);
 999   return it != frame.render_passes_by_id.end() ? it->second : NULL;
1000 }
1001
1002 static void RemoveRenderPassesRecursive(RenderPassId remove_render_pass_id,
1003                                         LayerTreeHostImpl::FrameData* frame) {
1004   RenderPass* remove_render_pass =
1005       FindRenderPassById(remove_render_pass_id, *frame);
1006   // The pass was already removed by another quad - probably the original, and
1007   // we are the replica.
1008   if (!remove_render_pass)
1009     return;
1010   RenderPassList& render_passes = frame->render_passes;
1011   RenderPassList::iterator to_remove = std::find(render_passes.begin(),
1012                                                  render_passes.end(),
1013                                                  remove_render_pass);
1014
1015   DCHECK(to_remove != render_passes.end());
1016
1017   scoped_ptr<RenderPass> removed_pass = render_passes.take(to_remove);
1018   frame->render_passes.erase(to_remove);
1019   frame->render_passes_by_id.erase(remove_render_pass_id);
1020
1021   // Now follow up for all RenderPass quads and remove their RenderPasses
1022   // recursively.
1023   const QuadList& quad_list = removed_pass->quad_list;
1024   QuadList::ConstBackToFrontIterator quad_list_iterator =
1025       quad_list.BackToFrontBegin();
1026   for (; quad_list_iterator != quad_list.BackToFrontEnd();
1027        ++quad_list_iterator) {
1028     DrawQuad* current_quad = (*quad_list_iterator);
1029     if (current_quad->material != DrawQuad::RENDER_PASS)
1030       continue;
1031
1032     RenderPassId next_remove_render_pass_id =
1033         RenderPassDrawQuad::MaterialCast(current_quad)->render_pass_id;
1034     RemoveRenderPassesRecursive(next_remove_render_pass_id, frame);
1035   }
1036 }
1037
1038 bool LayerTreeHostImpl::CullRenderPassesWithNoQuads::ShouldRemoveRenderPass(
1039     const RenderPassDrawQuad& quad, const FrameData& frame) const {
1040   const RenderPass* render_pass =
1041       FindRenderPassById(quad.render_pass_id, frame);
1042   if (!render_pass)
1043     return false;
1044
1045   // If any quad or RenderPass draws into this RenderPass, then keep it.
1046   const QuadList& quad_list = render_pass->quad_list;
1047   for (QuadList::ConstBackToFrontIterator quad_list_iterator =
1048            quad_list.BackToFrontBegin();
1049        quad_list_iterator != quad_list.BackToFrontEnd();
1050        ++quad_list_iterator) {
1051     DrawQuad* current_quad = *quad_list_iterator;
1052
1053     if (current_quad->material != DrawQuad::RENDER_PASS)
1054       return false;
1055
1056     const RenderPass* contributing_pass = FindRenderPassById(
1057         RenderPassDrawQuad::MaterialCast(current_quad)->render_pass_id, frame);
1058     if (contributing_pass)
1059       return false;
1060   }
1061   return true;
1062 }
1063
1064 // Defined for linking tests.
1065 template CC_EXPORT void LayerTreeHostImpl::RemoveRenderPasses<
1066   LayerTreeHostImpl::CullRenderPassesWithNoQuads>(
1067       CullRenderPassesWithNoQuads culler, FrameData*);
1068
1069 // static
1070 template <typename RenderPassCuller>
1071 void LayerTreeHostImpl::RemoveRenderPasses(RenderPassCuller culler,
1072                                            FrameData* frame) {
1073   for (size_t it = culler.RenderPassListBegin(frame->render_passes);
1074        it != culler.RenderPassListEnd(frame->render_passes);
1075        it = culler.RenderPassListNext(it)) {
1076     const RenderPass* current_pass = frame->render_passes[it];
1077     const QuadList& quad_list = current_pass->quad_list;
1078     QuadList::ConstBackToFrontIterator quad_list_iterator =
1079         quad_list.BackToFrontBegin();
1080
1081     for (; quad_list_iterator != quad_list.BackToFrontEnd();
1082          ++quad_list_iterator) {
1083       DrawQuad* current_quad = *quad_list_iterator;
1084
1085       if (current_quad->material != DrawQuad::RENDER_PASS)
1086         continue;
1087
1088       const RenderPassDrawQuad* render_pass_quad =
1089           RenderPassDrawQuad::MaterialCast(current_quad);
1090       if (!culler.ShouldRemoveRenderPass(*render_pass_quad, *frame))
1091         continue;
1092
1093       // We are changing the vector in the middle of iteration. Because we
1094       // delete render passes that draw into the current pass, we are
1095       // guaranteed that any data from the iterator to the end will not
1096       // change. So, capture the iterator position from the end of the
1097       // list, and restore it after the change.
1098       size_t position_from_end = frame->render_passes.size() - it;
1099       RemoveRenderPassesRecursive(render_pass_quad->render_pass_id, frame);
1100       it = frame->render_passes.size() - position_from_end;
1101       DCHECK_GE(frame->render_passes.size(), position_from_end);
1102     }
1103   }
1104 }
1105
1106 DrawResult LayerTreeHostImpl::PrepareToDraw(FrameData* frame) {
1107   TRACE_EVENT1("cc",
1108                "LayerTreeHostImpl::PrepareToDraw",
1109                "SourceFrameNumber",
1110                active_tree_->source_frame_number());
1111
1112   if (need_to_update_visible_tiles_before_draw_ &&
1113       tile_manager_ && tile_manager_->UpdateVisibleTiles()) {
1114     DidInitializeVisibleTile();
1115   }
1116   need_to_update_visible_tiles_before_draw_ = true;
1117
1118   UMA_HISTOGRAM_CUSTOM_COUNTS(
1119       "Compositing.NumActiveLayers", active_tree_->NumLayers(), 1, 400, 20);
1120
1121   bool ok = active_tree_->UpdateDrawProperties();
1122   DCHECK(ok) << "UpdateDrawProperties failed during draw";
1123
1124   frame->render_surface_layer_list = &active_tree_->RenderSurfaceLayerList();
1125   frame->render_passes.clear();
1126   frame->render_passes_by_id.clear();
1127   frame->will_draw_layers.clear();
1128   frame->contains_incomplete_tile = false;
1129   frame->has_no_damage = false;
1130
1131   if (active_tree_->root_layer()) {
1132     gfx::Rect device_viewport_damage_rect = viewport_damage_rect_;
1133     viewport_damage_rect_ = gfx::Rect();
1134
1135     active_tree_->root_layer()->render_surface()->damage_tracker()->
1136         AddDamageNextUpdate(device_viewport_damage_rect);
1137   }
1138
1139   DrawResult draw_result = CalculateRenderPasses(frame);
1140   if (draw_result != DRAW_SUCCESS) {
1141     DCHECK(!output_surface_->capabilities()
1142                .draw_and_swap_full_viewport_every_frame);
1143     return draw_result;
1144   }
1145
1146   // If we return DRAW_SUCCESS, then we expect DrawLayers() to be called before
1147   // this function is called again.
1148   return draw_result;
1149 }
1150
1151 void LayerTreeHostImpl::EvictTexturesForTesting() {
1152   EnforceManagedMemoryPolicy(ManagedMemoryPolicy(0));
1153 }
1154
1155 void LayerTreeHostImpl::BlockNotifyReadyToActivateForTesting(bool block) {
1156   NOTREACHED();
1157 }
1158
1159 void LayerTreeHostImpl::DidInitializeVisibleTileForTesting() {
1160   // Add arbitrary damage, to trigger prepare-to-draws.
1161   // Here, setting damage as viewport size, used only for testing.
1162   SetFullRootLayerDamage();
1163   DidInitializeVisibleTile();
1164 }
1165
1166 void LayerTreeHostImpl::ResetTreesForTesting() {
1167   if (active_tree_)
1168     active_tree_->DetachLayerTree();
1169   active_tree_ = LayerTreeImpl::create(this);
1170   if (pending_tree_)
1171     pending_tree_->DetachLayerTree();
1172   pending_tree_.reset();
1173   if (recycle_tree_)
1174     recycle_tree_->DetachLayerTree();
1175   recycle_tree_.reset();
1176 }
1177
1178 void LayerTreeHostImpl::ResetRecycleTreeForTesting() {
1179   if (recycle_tree_)
1180     recycle_tree_->DetachLayerTree();
1181   recycle_tree_.reset();
1182 }
1183
1184 void LayerTreeHostImpl::EnforceManagedMemoryPolicy(
1185     const ManagedMemoryPolicy& policy) {
1186
1187   bool evicted_resources = client_->ReduceContentsTextureMemoryOnImplThread(
1188       visible_ ? policy.bytes_limit_when_visible : 0,
1189       ManagedMemoryPolicy::PriorityCutoffToValue(
1190           visible_ ? policy.priority_cutoff_when_visible
1191                    : gpu::MemoryAllocation::CUTOFF_ALLOW_NOTHING));
1192   if (evicted_resources) {
1193     active_tree_->SetContentsTexturesPurged();
1194     if (pending_tree_)
1195       pending_tree_->SetContentsTexturesPurged();
1196     client_->SetNeedsCommitOnImplThread();
1197     client_->OnCanDrawStateChanged(CanDraw());
1198     client_->RenewTreePriority();
1199   }
1200
1201   UpdateTileManagerMemoryPolicy(policy);
1202 }
1203
1204 void LayerTreeHostImpl::UpdateTileManagerMemoryPolicy(
1205     const ManagedMemoryPolicy& policy) {
1206   if (!tile_manager_)
1207     return;
1208
1209   global_tile_state_.hard_memory_limit_in_bytes = 0;
1210   global_tile_state_.soft_memory_limit_in_bytes = 0;
1211   if (visible_ && policy.bytes_limit_when_visible > 0) {
1212     global_tile_state_.hard_memory_limit_in_bytes =
1213         policy.bytes_limit_when_visible;
1214     global_tile_state_.soft_memory_limit_in_bytes =
1215         (static_cast<int64>(global_tile_state_.hard_memory_limit_in_bytes) *
1216          settings_.max_memory_for_prepaint_percentage) /
1217         100;
1218   }
1219   global_tile_state_.memory_limit_policy =
1220       ManagedMemoryPolicy::PriorityCutoffToTileMemoryLimitPolicy(
1221           visible_ ?
1222           policy.priority_cutoff_when_visible :
1223           gpu::MemoryAllocation::CUTOFF_ALLOW_NOTHING);
1224   global_tile_state_.num_resources_limit = policy.num_resources_limit;
1225
1226   // TODO(reveman): We should avoid keeping around unused resources if
1227   // possible. crbug.com/224475
1228   // Unused limit is calculated from soft-limit, as hard-limit may
1229   // be very high and shouldn't typically be exceeded.
1230   size_t unused_memory_limit_in_bytes = static_cast<size_t>(
1231       (static_cast<int64>(global_tile_state_.soft_memory_limit_in_bytes) *
1232        settings_.max_unused_resource_memory_percentage) /
1233       100);
1234
1235   DCHECK(resource_pool_);
1236   resource_pool_->CheckBusyResources();
1237   // Soft limit is used for resource pool such that memory returns to soft
1238   // limit after going over.
1239   resource_pool_->SetResourceUsageLimits(
1240       global_tile_state_.soft_memory_limit_in_bytes,
1241       unused_memory_limit_in_bytes,
1242       global_tile_state_.num_resources_limit);
1243
1244   // Staging pool resources are used as transfer buffers so we use
1245   // |transfer_buffer_memory_limit_| as the memory limit for this resource pool.
1246   if (staging_resource_pool_) {
1247     staging_resource_pool_->CheckBusyResources();
1248     staging_resource_pool_->SetResourceUsageLimits(
1249         visible_ ? transfer_buffer_memory_limit_ : 0,
1250         transfer_buffer_memory_limit_,
1251         std::numeric_limits<size_t>::max());
1252   }
1253
1254   DidModifyTilePriorities();
1255 }
1256
1257 void LayerTreeHostImpl::DidModifyTilePriorities() {
1258   DCHECK(settings_.impl_side_painting);
1259   // Mark priorities as dirty and schedule a ManageTiles().
1260   tile_priorities_dirty_ = true;
1261   client_->SetNeedsManageTilesOnImplThread();
1262 }
1263
1264 void LayerTreeHostImpl::DidInitializeVisibleTile() {
1265   if (client_ && !client_->IsInsideDraw())
1266     client_->DidInitializeVisibleTileOnImplThread();
1267 }
1268
1269 void LayerTreeHostImpl::GetPictureLayerImplPairs(
1270     std::vector<PictureLayerImpl::Pair>* layer_pairs) const {
1271   DCHECK(layer_pairs->empty());
1272   for (std::vector<PictureLayerImpl*>::const_iterator it =
1273            picture_layers_.begin();
1274        it != picture_layers_.end();
1275        ++it) {
1276     PictureLayerImpl* layer = *it;
1277
1278     // TODO(vmpstr): Iterators and should handle this instead. crbug.com/381704
1279     if (!layer->HasValidTilePriorities())
1280       continue;
1281
1282     PictureLayerImpl* twin_layer = layer->GetTwinLayer();
1283
1284     // Ignore the twin layer when tile priorities are invalid.
1285     // TODO(vmpstr): Iterators should handle this instead. crbug.com/381704
1286     if (twin_layer && !twin_layer->HasValidTilePriorities())
1287       twin_layer = NULL;
1288
1289     // If the current tree is ACTIVE_TREE, then always generate a layer_pair.
1290     // If current tree is PENDING_TREE, then only generate a layer_pair if
1291     // there is no twin layer.
1292     if (layer->GetTree() == ACTIVE_TREE) {
1293       DCHECK(!twin_layer || twin_layer->GetTree() == PENDING_TREE);
1294       layer_pairs->push_back(PictureLayerImpl::Pair(layer, twin_layer));
1295     } else if (!twin_layer) {
1296       layer_pairs->push_back(PictureLayerImpl::Pair(NULL, layer));
1297     }
1298   }
1299 }
1300
1301 void LayerTreeHostImpl::BuildRasterQueue(RasterTilePriorityQueue* queue,
1302                                          TreePriority tree_priority) {
1303   picture_layer_pairs_.clear();
1304   GetPictureLayerImplPairs(&picture_layer_pairs_);
1305   queue->Build(picture_layer_pairs_, tree_priority);
1306 }
1307
1308 void LayerTreeHostImpl::BuildEvictionQueue(EvictionTilePriorityQueue* queue,
1309                                            TreePriority tree_priority) {
1310   picture_layer_pairs_.clear();
1311   GetPictureLayerImplPairs(&picture_layer_pairs_);
1312   queue->Build(picture_layer_pairs_, tree_priority);
1313 }
1314
1315 const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers()
1316     const {
1317   return picture_layers_;
1318 }
1319
1320 void LayerTreeHostImpl::NotifyReadyToActivate() {
1321   client_->NotifyReadyToActivate();
1322 }
1323
1324 void LayerTreeHostImpl::NotifyTileStateChanged(const Tile* tile) {
1325   TRACE_EVENT0("cc", "LayerTreeHostImpl::NotifyTileStateChanged");
1326
1327   if (active_tree_) {
1328     LayerImpl* layer_impl =
1329         active_tree_->FindActiveTreeLayerById(tile->layer_id());
1330     if (layer_impl)
1331       layer_impl->NotifyTileStateChanged(tile);
1332   }
1333
1334   if (pending_tree_) {
1335     LayerImpl* layer_impl =
1336         pending_tree_->FindPendingTreeLayerById(tile->layer_id());
1337     if (layer_impl)
1338       layer_impl->NotifyTileStateChanged(tile);
1339   }
1340 }
1341
1342 void LayerTreeHostImpl::SetMemoryPolicy(const ManagedMemoryPolicy& policy) {
1343   SetManagedMemoryPolicy(policy, zero_budget_);
1344 }
1345
1346 void LayerTreeHostImpl::SetTreeActivationCallback(
1347     const base::Closure& callback) {
1348   DCHECK(proxy_->IsImplThread());
1349   DCHECK(settings_.impl_side_painting || callback.is_null());
1350   tree_activation_callback_ = callback;
1351 }
1352
1353 void LayerTreeHostImpl::SetManagedMemoryPolicy(
1354     const ManagedMemoryPolicy& policy, bool zero_budget) {
1355   if (cached_managed_memory_policy_ == policy && zero_budget_ == zero_budget)
1356     return;
1357
1358   ManagedMemoryPolicy old_policy = ActualManagedMemoryPolicy();
1359
1360   cached_managed_memory_policy_ = policy;
1361   zero_budget_ = zero_budget;
1362   ManagedMemoryPolicy actual_policy = ActualManagedMemoryPolicy();
1363
1364   if (old_policy == actual_policy)
1365     return;
1366
1367   if (!proxy_->HasImplThread()) {
1368     // In single-thread mode, this can be called on the main thread by
1369     // GLRenderer::OnMemoryAllocationChanged.
1370     DebugScopedSetImplThread impl_thread(proxy_);
1371     EnforceManagedMemoryPolicy(actual_policy);
1372   } else {
1373     DCHECK(proxy_->IsImplThread());
1374     EnforceManagedMemoryPolicy(actual_policy);
1375   }
1376
1377   // If there is already enough memory to draw everything imaginable and the
1378   // new memory limit does not change this, then do not re-commit. Don't bother
1379   // skipping commits if this is not visible (commits don't happen when not
1380   // visible, there will almost always be a commit when this becomes visible).
1381   bool needs_commit = true;
1382   if (visible() &&
1383       actual_policy.bytes_limit_when_visible >= max_memory_needed_bytes_ &&
1384       old_policy.bytes_limit_when_visible >= max_memory_needed_bytes_ &&
1385       actual_policy.priority_cutoff_when_visible ==
1386           old_policy.priority_cutoff_when_visible) {
1387     needs_commit = false;
1388   }
1389
1390   if (needs_commit)
1391     client_->SetNeedsCommitOnImplThread();
1392 }
1393
1394 void LayerTreeHostImpl::SetExternalDrawConstraints(
1395     const gfx::Transform& transform,
1396     const gfx::Rect& viewport,
1397     const gfx::Rect& clip,
1398     const gfx::Rect& viewport_rect_for_tile_priority,
1399     const gfx::Transform& transform_for_tile_priority,
1400     bool resourceless_software_draw) {
1401   gfx::Rect viewport_rect_for_tile_priority_in_view_space;
1402   if (!resourceless_software_draw) {
1403     gfx::Transform screen_to_view(gfx::Transform::kSkipInitialization);
1404     if (transform_for_tile_priority.GetInverse(&screen_to_view)) {
1405       // Convert from screen space to view space.
1406       viewport_rect_for_tile_priority_in_view_space =
1407           gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
1408               screen_to_view, viewport_rect_for_tile_priority));
1409     }
1410   }
1411
1412   if (external_transform_ != transform || external_viewport_ != viewport ||
1413       resourceless_software_draw_ != resourceless_software_draw ||
1414       viewport_rect_for_tile_priority_ !=
1415           viewport_rect_for_tile_priority_in_view_space) {
1416     active_tree_->set_needs_update_draw_properties();
1417   }
1418
1419   external_transform_ = transform;
1420   external_viewport_ = viewport;
1421   external_clip_ = clip;
1422   viewport_rect_for_tile_priority_ =
1423       viewport_rect_for_tile_priority_in_view_space;
1424   resourceless_software_draw_ = resourceless_software_draw;
1425 }
1426
1427 void LayerTreeHostImpl::SetNeedsRedrawRect(const gfx::Rect& damage_rect) {
1428   if (damage_rect.IsEmpty())
1429     return;
1430   NotifySwapPromiseMonitorsOfSetNeedsRedraw();
1431   client_->SetNeedsRedrawRectOnImplThread(damage_rect);
1432 }
1433
1434 void LayerTreeHostImpl::BeginFrame(const BeginFrameArgs& args) {
1435   client_->BeginFrame(args);
1436 }
1437
1438 void LayerTreeHostImpl::DidSwapBuffers() {
1439   client_->DidSwapBuffersOnImplThread();
1440 }
1441
1442 void LayerTreeHostImpl::DidSwapBuffersComplete() {
1443   client_->DidSwapBuffersCompleteOnImplThread();
1444 }
1445
1446 void LayerTreeHostImpl::ReclaimResources(const CompositorFrameAck* ack) {
1447   // TODO(piman): We may need to do some validation on this ack before
1448   // processing it.
1449   if (renderer_)
1450     renderer_->ReceiveSwapBuffersAck(*ack);
1451
1452   // In OOM, we now might be able to release more resources that were held
1453   // because they were exported.
1454   if (tile_manager_) {
1455     DCHECK(resource_pool_);
1456
1457     resource_pool_->CheckBusyResources();
1458     resource_pool_->ReduceResourceUsage();
1459   }
1460   // If we're not visible, we likely released resources, so we want to
1461   // aggressively flush here to make sure those DeleteTextures make it to the
1462   // GPU process to free up the memory.
1463   if (output_surface_->context_provider() && !visible_) {
1464     output_surface_->context_provider()->ContextGL()->ShallowFlushCHROMIUM();
1465   }
1466 }
1467
1468 void LayerTreeHostImpl::OnCanDrawStateChangedForTree() {
1469   client_->OnCanDrawStateChanged(CanDraw());
1470 }
1471
1472 CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
1473   CompositorFrameMetadata metadata;
1474   metadata.device_scale_factor = device_scale_factor_;
1475   metadata.page_scale_factor = active_tree_->total_page_scale_factor();
1476   metadata.scrollable_viewport_size = active_tree_->ScrollableViewportSize();
1477   metadata.root_layer_size = active_tree_->ScrollableSize();
1478   metadata.min_page_scale_factor = active_tree_->min_page_scale_factor();
1479   metadata.max_page_scale_factor = active_tree_->max_page_scale_factor();
1480   if (top_controls_manager_) {
1481     metadata.location_bar_offset =
1482         gfx::Vector2dF(0.f, top_controls_manager_->controls_top_offset());
1483     metadata.location_bar_content_translation =
1484         gfx::Vector2dF(0.f, top_controls_manager_->content_top_offset());
1485   }
1486
1487   active_tree_->GetViewportSelection(&metadata.selection_start,
1488                                      &metadata.selection_end);
1489
1490   if (!InnerViewportScrollLayer())
1491     return metadata;
1492
1493   metadata.root_scroll_offset = active_tree_->TotalScrollOffset();
1494
1495   return metadata;
1496 }
1497
1498 static void LayerTreeHostImplDidBeginTracingCallback(LayerImpl* layer) {
1499   layer->DidBeginTracing();
1500 }
1501
1502 void LayerTreeHostImpl::DrawLayers(FrameData* frame,
1503                                    base::TimeTicks frame_begin_time) {
1504   TRACE_EVENT0("cc", "LayerTreeHostImpl::DrawLayers");
1505   DCHECK(CanDraw());
1506
1507   if (frame->has_no_damage) {
1508     TRACE_EVENT_INSTANT0("cc", "EarlyOut_NoDamage", TRACE_EVENT_SCOPE_THREAD);
1509     DCHECK(!output_surface_->capabilities()
1510                .draw_and_swap_full_viewport_every_frame);
1511     return;
1512   }
1513
1514   DCHECK(!frame->render_passes.empty());
1515
1516   fps_counter_->SaveTimeStamp(frame_begin_time,
1517                               !output_surface_->context_provider());
1518   bool on_main_thread = false;
1519   rendering_stats_instrumentation_->IncrementFrameCount(
1520       1, on_main_thread);
1521
1522   if (tile_manager_) {
1523     memory_history_->SaveEntry(
1524         tile_manager_->memory_stats_from_last_assign());
1525   }
1526
1527   if (debug_state_.ShowHudRects()) {
1528     debug_rect_history_->SaveDebugRectsForCurrentFrame(
1529         active_tree_->root_layer(),
1530         active_tree_->hud_layer(),
1531         *frame->render_surface_layer_list,
1532         frame->occluding_screen_space_rects,
1533         frame->non_occluding_screen_space_rects,
1534         debug_state_);
1535   }
1536
1537   if (!settings_.impl_side_painting && debug_state_.continuous_painting) {
1538     const RenderingStats& stats =
1539         rendering_stats_instrumentation_->GetRenderingStats();
1540     paint_time_counter_->SavePaintTime(stats.main_stats.paint_time);
1541   }
1542
1543   bool is_new_trace;
1544   TRACE_EVENT_IS_NEW_TRACE(&is_new_trace);
1545   if (is_new_trace) {
1546     if (pending_tree_) {
1547       LayerTreeHostCommon::CallFunctionForSubtree(
1548           pending_tree_->root_layer(),
1549           base::Bind(&LayerTreeHostImplDidBeginTracingCallback));
1550     }
1551     LayerTreeHostCommon::CallFunctionForSubtree(
1552         active_tree_->root_layer(),
1553         base::Bind(&LayerTreeHostImplDidBeginTracingCallback));
1554   }
1555
1556   {
1557     TRACE_EVENT0("cc", "DrawLayers.FrameViewerTracing");
1558     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
1559        TRACE_DISABLED_BY_DEFAULT("cc.debug") ","
1560        TRACE_DISABLED_BY_DEFAULT("cc.debug.quads") ","
1561        TRACE_DISABLED_BY_DEFAULT("devtools.timeline.layers"),
1562        "cc::LayerTreeHostImpl",
1563        id_,
1564        AsValueWithFrame(frame));
1565   }
1566
1567   const DrawMode draw_mode = GetDrawMode();
1568
1569   // Because the contents of the HUD depend on everything else in the frame, the
1570   // contents of its texture are updated as the last thing before the frame is
1571   // drawn.
1572   if (active_tree_->hud_layer()) {
1573     TRACE_EVENT0("cc", "DrawLayers.UpdateHudTexture");
1574     active_tree_->hud_layer()->UpdateHudTexture(draw_mode,
1575                                                 resource_provider_.get());
1576   }
1577
1578   if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE) {
1579     bool disable_picture_quad_image_filtering =
1580         IsCurrentlyScrolling() || needs_animate_layers();
1581
1582     scoped_ptr<SoftwareRenderer> temp_software_renderer =
1583         SoftwareRenderer::Create(this, &settings_, output_surface_.get(), NULL);
1584     temp_software_renderer->DrawFrame(&frame->render_passes,
1585                                       device_scale_factor_,
1586                                       DeviceViewport(),
1587                                       DeviceClip(),
1588                                       disable_picture_quad_image_filtering);
1589   } else {
1590     renderer_->DrawFrame(&frame->render_passes,
1591                          device_scale_factor_,
1592                          DeviceViewport(),
1593                          DeviceClip(),
1594                          false);
1595   }
1596   // The render passes should be consumed by the renderer.
1597   DCHECK(frame->render_passes.empty());
1598   frame->render_passes_by_id.clear();
1599
1600   // The next frame should start by assuming nothing has changed, and changes
1601   // are noted as they occur.
1602   // TODO(boliu): If we did a temporary software renderer frame, propogate the
1603   // damage forward to the next frame.
1604   for (size_t i = 0; i < frame->render_surface_layer_list->size(); i++) {
1605     (*frame->render_surface_layer_list)[i]->render_surface()->damage_tracker()->
1606         DidDrawDamagedArea();
1607   }
1608   active_tree_->root_layer()->ResetAllChangeTrackingForSubtree();
1609
1610   active_tree_->set_has_ever_been_drawn(true);
1611   devtools_instrumentation::DidDrawFrame(id_);
1612   benchmark_instrumentation::IssueImplThreadRenderingStatsEvent(
1613       rendering_stats_instrumentation_->impl_thread_rendering_stats());
1614   rendering_stats_instrumentation_->AccumulateAndClearImplThreadStats();
1615 }
1616
1617 void LayerTreeHostImpl::DidDrawAllLayers(const FrameData& frame) {
1618   for (size_t i = 0; i < frame.will_draw_layers.size(); ++i)
1619     frame.will_draw_layers[i]->DidDraw(resource_provider_.get());
1620
1621   // Once all layers have been drawn, pending texture uploads should no
1622   // longer block future uploads.
1623   resource_provider_->MarkPendingUploadsAsNonBlocking();
1624 }
1625
1626 void LayerTreeHostImpl::FinishAllRendering() {
1627   if (renderer_)
1628     renderer_->Finish();
1629 }
1630
1631 void LayerTreeHostImpl::SetUseGpuRasterization(bool use_gpu) {
1632   if (use_gpu == use_gpu_rasterization_)
1633     return;
1634
1635   use_gpu_rasterization_ = use_gpu;
1636   ReleaseTreeResources();
1637
1638   // Replace existing tile manager with another one that uses appropriate
1639   // rasterizer.
1640   if (tile_manager_) {
1641     DestroyTileManager();
1642     CreateAndSetTileManager();
1643   }
1644
1645   // We have released tilings for both active and pending tree.
1646   // We would not have any content to draw until the pending tree is activated.
1647   // Prevent the active tree from drawing until activation.
1648   active_tree_->SetRequiresHighResToDraw();
1649 }
1650
1651 const RendererCapabilitiesImpl&
1652 LayerTreeHostImpl::GetRendererCapabilities() const {
1653   return renderer_->Capabilities();
1654 }
1655
1656 bool LayerTreeHostImpl::SwapBuffers(const LayerTreeHostImpl::FrameData& frame) {
1657   active_tree()->ResetRequiresHighResToDraw();
1658   if (frame.has_no_damage) {
1659     active_tree()->BreakSwapPromises(SwapPromise::SWAP_FAILS);
1660     return false;
1661   }
1662   CompositorFrameMetadata metadata = MakeCompositorFrameMetadata();
1663   active_tree()->FinishSwapPromises(&metadata);
1664   for (size_t i = 0; i < metadata.latency_info.size(); i++) {
1665     TRACE_EVENT_FLOW_STEP0(
1666         "input",
1667         "LatencyInfo.Flow",
1668         TRACE_ID_DONT_MANGLE(metadata.latency_info[i].trace_id),
1669         "SwapBuffers");
1670   }
1671   renderer_->SwapBuffers(metadata);
1672   return true;
1673 }
1674
1675 void LayerTreeHostImpl::SetNeedsBeginFrame(bool enable) {
1676   if (output_surface_)
1677     output_surface_->SetNeedsBeginFrame(enable);
1678   else
1679     DCHECK(!enable);
1680 }
1681
1682 void LayerTreeHostImpl::WillBeginImplFrame(const BeginFrameArgs& args) {
1683   // Sample the frame time now. This time will be used for updating animations
1684   // when we draw.
1685   UpdateCurrentBeginFrameArgs(args);
1686   // Cache the begin impl frame interval
1687   begin_impl_frame_interval_ = args.interval;
1688 }
1689
1690 void LayerTreeHostImpl::UpdateInnerViewportContainerSize() {
1691   LayerImpl* container_layer = active_tree_->InnerViewportContainerLayer();
1692   if (!container_layer)
1693     return;
1694
1695   if (top_controls_manager_)
1696     container_layer->SetBoundsDelta(
1697         gfx::Vector2dF(0,
1698                        top_controls_layout_height_ -
1699                            top_controls_manager_->content_top_offset()));
1700 }
1701
1702 void LayerTreeHostImpl::DidLoseOutputSurface() {
1703   if (resource_provider_)
1704     resource_provider_->DidLoseOutputSurface();
1705   client_->DidLoseOutputSurfaceOnImplThread();
1706 }
1707
1708 bool LayerTreeHostImpl::HaveRootScrollLayer() const {
1709   return !!InnerViewportScrollLayer();
1710 }
1711
1712 LayerImpl* LayerTreeHostImpl::RootLayer() const {
1713   return active_tree_->root_layer();
1714 }
1715
1716 LayerImpl* LayerTreeHostImpl::InnerViewportScrollLayer() const {
1717   return active_tree_->InnerViewportScrollLayer();
1718 }
1719
1720 LayerImpl* LayerTreeHostImpl::OuterViewportScrollLayer() const {
1721   return active_tree_->OuterViewportScrollLayer();
1722 }
1723
1724 LayerImpl* LayerTreeHostImpl::CurrentlyScrollingLayer() const {
1725   return active_tree_->CurrentlyScrollingLayer();
1726 }
1727
1728 bool LayerTreeHostImpl::IsCurrentlyScrolling() const {
1729   return CurrentlyScrollingLayer() ||
1730          (InnerViewportScrollLayer() &&
1731           InnerViewportScrollLayer()->IsExternalFlingActive()) ||
1732          (OuterViewportScrollLayer() &&
1733           OuterViewportScrollLayer()->IsExternalFlingActive());
1734 }
1735
1736 // Content layers can be either directly scrollable or contained in an outer
1737 // scrolling layer which applies the scroll transform. Given a content layer,
1738 // this function returns the associated scroll layer if any.
1739 static LayerImpl* FindScrollLayerForContentLayer(LayerImpl* layer_impl) {
1740   if (!layer_impl)
1741     return NULL;
1742
1743   if (layer_impl->scrollable())
1744     return layer_impl;
1745
1746   if (layer_impl->DrawsContent() &&
1747       layer_impl->parent() &&
1748       layer_impl->parent()->scrollable())
1749     return layer_impl->parent();
1750
1751   return NULL;
1752 }
1753
1754 void LayerTreeHostImpl::CreatePendingTree() {
1755   CHECK(!pending_tree_);
1756   if (recycle_tree_)
1757     recycle_tree_.swap(pending_tree_);
1758   else
1759     pending_tree_ = LayerTreeImpl::create(this);
1760
1761   // Update the delta from the active tree, which may have
1762   // adjusted its delta prior to the pending tree being created.
1763   DCHECK_EQ(1.f, pending_tree_->sent_page_scale_delta());
1764   pending_tree_->SetPageScaleDelta(active_tree_->page_scale_delta() /
1765                                    active_tree_->sent_page_scale_delta());
1766
1767   client_->OnCanDrawStateChanged(CanDraw());
1768   TRACE_EVENT_ASYNC_BEGIN0("cc", "PendingTree:waiting", pending_tree_.get());
1769 }
1770
1771 void LayerTreeHostImpl::UpdateVisibleTiles() {
1772   if (tile_manager_ && tile_manager_->UpdateVisibleTiles())
1773     DidInitializeVisibleTile();
1774   need_to_update_visible_tiles_before_draw_ = false;
1775 }
1776
1777 void LayerTreeHostImpl::ActivateSyncTree() {
1778   need_to_update_visible_tiles_before_draw_ = true;
1779
1780   if (pending_tree_) {
1781     TRACE_EVENT_ASYNC_END0("cc", "PendingTree:waiting", pending_tree_.get());
1782
1783     active_tree_->SetRootLayerScrollOffsetDelegate(NULL);
1784     active_tree_->PushPersistedState(pending_tree_.get());
1785     // Process any requests in the UI resource queue.  The request queue is
1786     // given in LayerTreeHost::FinishCommitOnImplThread.  This must take place
1787     // before the swap.
1788     pending_tree_->ProcessUIResourceRequestQueue();
1789
1790     if (pending_tree_->needs_full_tree_sync()) {
1791       active_tree_->SetRootLayer(
1792           TreeSynchronizer::SynchronizeTrees(pending_tree_->root_layer(),
1793                                              active_tree_->DetachLayerTree(),
1794                                              active_tree_.get()));
1795     }
1796     TreeSynchronizer::PushProperties(pending_tree_->root_layer(),
1797                                      active_tree_->root_layer());
1798     pending_tree_->PushPropertiesTo(active_tree_.get());
1799
1800     // Now that we've synced everything from the pending tree to the active
1801     // tree, rename the pending tree the recycle tree so we can reuse it on the
1802     // next sync.
1803     DCHECK(!recycle_tree_);
1804     pending_tree_.swap(recycle_tree_);
1805
1806     active_tree_->SetRootLayerScrollOffsetDelegate(
1807         root_layer_scroll_offset_delegate_);
1808     UpdateInnerViewportContainerSize();
1809   } else {
1810     active_tree_->ProcessUIResourceRequestQueue();
1811   }
1812
1813   active_tree_->DidBecomeActive();
1814   ActivateAnimations();
1815   if (settings_.impl_side_painting)
1816     client_->RenewTreePriority();
1817
1818   client_->OnCanDrawStateChanged(CanDraw());
1819   client_->DidActivateSyncTree();
1820   if (!tree_activation_callback_.is_null())
1821     tree_activation_callback_.Run();
1822
1823   if (debug_state_.continuous_painting) {
1824     const RenderingStats& stats =
1825         rendering_stats_instrumentation_->GetRenderingStats();
1826     paint_time_counter_->SavePaintTime(stats.main_stats.paint_time +
1827                                        stats.main_stats.record_time +
1828                                        stats.impl_stats.rasterize_time);
1829   }
1830
1831   if (time_source_client_adapter_ && time_source_client_adapter_->Active())
1832     DCHECK(active_tree_->root_layer());
1833 }
1834
1835 void LayerTreeHostImpl::SetVisible(bool visible) {
1836   DCHECK(proxy_->IsImplThread());
1837
1838   if (visible_ == visible)
1839     return;
1840   visible_ = visible;
1841   DidVisibilityChange(this, visible_);
1842   EnforceManagedMemoryPolicy(ActualManagedMemoryPolicy());
1843
1844   // If we just became visible, we have to ensure that we draw high res tiles,
1845   // to prevent checkerboard/low res flashes.
1846   if (visible_)
1847     active_tree()->SetRequiresHighResToDraw();
1848   else
1849     EvictAllUIResources();
1850
1851   // Evict tiles immediately if invisible since this tab may never get another
1852   // draw or timer tick.
1853   if (!visible_)
1854     ManageTiles();
1855
1856   if (!renderer_)
1857     return;
1858
1859   renderer_->SetVisible(visible);
1860 }
1861
1862 void LayerTreeHostImpl::SetNeedsAnimate() {
1863   NotifySwapPromiseMonitorsOfSetNeedsRedraw();
1864   client_->SetNeedsAnimateOnImplThread();
1865 }
1866
1867 void LayerTreeHostImpl::SetNeedsRedraw() {
1868   NotifySwapPromiseMonitorsOfSetNeedsRedraw();
1869   client_->SetNeedsRedrawOnImplThread();
1870 }
1871
1872 ManagedMemoryPolicy LayerTreeHostImpl::ActualManagedMemoryPolicy() const {
1873   ManagedMemoryPolicy actual = cached_managed_memory_policy_;
1874   if (debug_state_.rasterize_only_visible_content) {
1875     actual.priority_cutoff_when_visible =
1876         gpu::MemoryAllocation::CUTOFF_ALLOW_REQUIRED_ONLY;
1877   } else if (use_gpu_rasterization()) {
1878     actual.priority_cutoff_when_visible =
1879         gpu::MemoryAllocation::CUTOFF_ALLOW_NICE_TO_HAVE;
1880   }
1881
1882   if (zero_budget_) {
1883     actual.bytes_limit_when_visible = 0;
1884   }
1885
1886   return actual;
1887 }
1888
1889 size_t LayerTreeHostImpl::memory_allocation_limit_bytes() const {
1890   return ActualManagedMemoryPolicy().bytes_limit_when_visible;
1891 }
1892
1893 int LayerTreeHostImpl::memory_allocation_priority_cutoff() const {
1894   return ManagedMemoryPolicy::PriorityCutoffToValue(
1895       ActualManagedMemoryPolicy().priority_cutoff_when_visible);
1896 }
1897
1898 void LayerTreeHostImpl::ReleaseTreeResources() {
1899   active_tree_->ReleaseResources();
1900   if (pending_tree_)
1901     pending_tree_->ReleaseResources();
1902   if (recycle_tree_)
1903     recycle_tree_->ReleaseResources();
1904
1905   EvictAllUIResources();
1906 }
1907
1908 void LayerTreeHostImpl::CreateAndSetRenderer() {
1909   DCHECK(!renderer_);
1910   DCHECK(output_surface_);
1911   DCHECK(resource_provider_);
1912
1913   if (output_surface_->capabilities().delegated_rendering) {
1914     renderer_ = DelegatingRenderer::Create(
1915         this, &settings_, output_surface_.get(), resource_provider_.get());
1916   } else if (output_surface_->context_provider()) {
1917     renderer_ = GLRenderer::Create(this,
1918                                    &settings_,
1919                                    output_surface_.get(),
1920                                    resource_provider_.get(),
1921                                    texture_mailbox_deleter_.get(),
1922                                    settings_.highp_threshold_min);
1923   } else if (output_surface_->software_device()) {
1924     renderer_ = SoftwareRenderer::Create(
1925         this, &settings_, output_surface_.get(), resource_provider_.get());
1926   }
1927   DCHECK(renderer_);
1928
1929   renderer_->SetVisible(visible_);
1930   SetFullRootLayerDamage();
1931
1932   // See note in LayerTreeImpl::UpdateDrawProperties.  Renderer needs to be
1933   // initialized to get max texture size.  Also, after releasing resources,
1934   // trees need another update to generate new ones.
1935   active_tree_->set_needs_update_draw_properties();
1936   if (pending_tree_)
1937     pending_tree_->set_needs_update_draw_properties();
1938   client_->UpdateRendererCapabilitiesOnImplThread();
1939 }
1940
1941 void LayerTreeHostImpl::CreateAndSetTileManager() {
1942   DCHECK(!tile_manager_);
1943   DCHECK(settings_.impl_side_painting);
1944   DCHECK(output_surface_);
1945   DCHECK(resource_provider_);
1946   DCHECK(proxy_->ImplThreadTaskRunner());
1947
1948   ContextProvider* context_provider = output_surface_->context_provider();
1949   transfer_buffer_memory_limit_ =
1950       GetMaxTransferBufferUsageBytes(context_provider, settings_.refresh_rate);
1951
1952   if (use_gpu_rasterization_ && context_provider) {
1953     resource_pool_ =
1954         ResourcePool::Create(resource_provider_.get(),
1955                              GL_TEXTURE_2D,
1956                              resource_provider_->best_texture_format());
1957
1958     raster_worker_pool_ =
1959         GpuRasterWorkerPool::Create(proxy_->ImplThreadTaskRunner(),
1960                                     context_provider,
1961                                     resource_provider_.get());
1962   } else if (UseOneCopyTextureUpload() && context_provider) {
1963     // We need to create a staging resource pool when using copy rasterizer.
1964     staging_resource_pool_ =
1965         ResourcePool::Create(resource_provider_.get(),
1966                              GetMapImageTextureTarget(context_provider),
1967                              resource_provider_->best_texture_format());
1968     resource_pool_ =
1969         ResourcePool::Create(resource_provider_.get(),
1970                              GL_TEXTURE_2D,
1971                              resource_provider_->best_texture_format());
1972
1973     raster_worker_pool_ = ImageCopyRasterWorkerPool::Create(
1974         proxy_->ImplThreadTaskRunner(),
1975         RasterWorkerPool::GetTaskGraphRunner(),
1976         context_provider,
1977         resource_provider_.get(),
1978         staging_resource_pool_.get());
1979   } else if (!UseZeroCopyTextureUpload() && context_provider) {
1980     resource_pool_ = ResourcePool::Create(
1981         resource_provider_.get(),
1982         GL_TEXTURE_2D,
1983         resource_provider_->memory_efficient_texture_format());
1984
1985     raster_worker_pool_ = PixelBufferRasterWorkerPool::Create(
1986         proxy_->ImplThreadTaskRunner(),
1987         RasterWorkerPool::GetTaskGraphRunner(),
1988         context_provider,
1989         resource_provider_.get(),
1990         transfer_buffer_memory_limit_);
1991   } else {
1992     resource_pool_ =
1993         ResourcePool::Create(resource_provider_.get(),
1994                              GetMapImageTextureTarget(context_provider),
1995                              resource_provider_->best_texture_format());
1996
1997     raster_worker_pool_ =
1998         ImageRasterWorkerPool::Create(proxy_->ImplThreadTaskRunner(),
1999                                       RasterWorkerPool::GetTaskGraphRunner(),
2000                                       resource_provider_.get());
2001   }
2002
2003   tile_manager_ =
2004       TileManager::Create(this,
2005                           proxy_->ImplThreadTaskRunner(),
2006                           resource_pool_.get(),
2007                           raster_worker_pool_->AsRasterizer(),
2008                           rendering_stats_instrumentation_);
2009
2010   UpdateTileManagerMemoryPolicy(ActualManagedMemoryPolicy());
2011   need_to_update_visible_tiles_before_draw_ = false;
2012 }
2013
2014 void LayerTreeHostImpl::DestroyTileManager() {
2015   tile_manager_.reset();
2016   resource_pool_.reset();
2017   staging_resource_pool_.reset();
2018   raster_worker_pool_.reset();
2019 }
2020
2021 bool LayerTreeHostImpl::UsePendingTreeForSync() const {
2022   // In impl-side painting, synchronize to the pending tree so that it has
2023   // time to raster before being displayed.
2024   return settings_.impl_side_painting;
2025 }
2026
2027 bool LayerTreeHostImpl::UseZeroCopyTextureUpload() const {
2028   // Note: we use zero-copy by default when the renderer is using
2029   // shared memory resources.
2030   return (settings_.use_zero_copy ||
2031           GetRendererCapabilities().using_shared_memory_resources) &&
2032          GetRendererCapabilities().using_map_image;
2033 }
2034
2035 bool LayerTreeHostImpl::UseOneCopyTextureUpload() const {
2036   // Sync query support is required by one-copy rasterizer.
2037   return settings_.use_one_copy && GetRendererCapabilities().using_map_image &&
2038          resource_provider_->use_sync_query();
2039 }
2040
2041 void LayerTreeHostImpl::EnforceZeroBudget(bool zero_budget) {
2042   SetManagedMemoryPolicy(cached_managed_memory_policy_, zero_budget);
2043 }
2044
2045 bool LayerTreeHostImpl::InitializeRenderer(
2046     scoped_ptr<OutputSurface> output_surface) {
2047   TRACE_EVENT0("cc", "LayerTreeHostImpl::InitializeRenderer");
2048
2049   // Since we will create a new resource provider, we cannot continue to use
2050   // the old resources (i.e. render_surfaces and texture IDs). Clear them
2051   // before we destroy the old resource provider.
2052   ReleaseTreeResources();
2053
2054   // Note: order is important here.
2055   renderer_.reset();
2056   DestroyTileManager();
2057   resource_provider_.reset();
2058   output_surface_.reset();
2059
2060   if (!output_surface->BindToClient(this))
2061     return false;
2062
2063   output_surface_ = output_surface.Pass();
2064   resource_provider_ =
2065       ResourceProvider::Create(output_surface_.get(),
2066                                shared_bitmap_manager_,
2067                                proxy_->blocking_main_thread_task_runner(),
2068                                settings_.highp_threshold_min,
2069                                settings_.use_rgba_4444_textures,
2070                                settings_.texture_id_allocation_chunk_size,
2071                                settings_.use_distance_field_text);
2072
2073   if (output_surface_->capabilities().deferred_gl_initialization)
2074     EnforceZeroBudget(true);
2075
2076   CreateAndSetRenderer();
2077
2078   if (settings_.impl_side_painting)
2079     CreateAndSetTileManager();
2080
2081   // Initialize vsync parameters to sane values.
2082   const base::TimeDelta display_refresh_interval =
2083       base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond /
2084                                         settings_.refresh_rate);
2085   CommitVSyncParameters(base::TimeTicks(), display_refresh_interval);
2086
2087   // TODO(brianderson): Don't use a hard-coded parent draw time.
2088   base::TimeDelta parent_draw_time =
2089       (!settings_.begin_frame_scheduling_enabled &&
2090        output_surface_->capabilities().adjust_deadline_for_parent)
2091           ? BeginFrameArgs::DefaultEstimatedParentDrawTime()
2092           : base::TimeDelta();
2093   client_->SetEstimatedParentDrawTime(parent_draw_time);
2094
2095   int max_frames_pending = output_surface_->capabilities().max_frames_pending;
2096   if (max_frames_pending <= 0)
2097     max_frames_pending = OutputSurface::DEFAULT_MAX_FRAMES_PENDING;
2098   client_->SetMaxSwapsPendingOnImplThread(max_frames_pending);
2099   client_->OnCanDrawStateChanged(CanDraw());
2100
2101   return true;
2102 }
2103
2104 void LayerTreeHostImpl::CommitVSyncParameters(base::TimeTicks timebase,
2105                                               base::TimeDelta interval) {
2106   client_->CommitVSyncParameters(timebase, interval);
2107 }
2108
2109 void LayerTreeHostImpl::DeferredInitialize() {
2110   DCHECK(output_surface_->capabilities().deferred_gl_initialization);
2111   DCHECK(settings_.impl_side_painting);
2112   DCHECK(output_surface_->context_provider());
2113
2114   ReleaseTreeResources();
2115   renderer_.reset();
2116   DestroyTileManager();
2117
2118   resource_provider_->InitializeGL();
2119
2120   CreateAndSetRenderer();
2121   EnforceZeroBudget(false);
2122   CreateAndSetTileManager();
2123
2124   client_->SetNeedsCommitOnImplThread();
2125 }
2126
2127 void LayerTreeHostImpl::ReleaseGL() {
2128   DCHECK(output_surface_->capabilities().deferred_gl_initialization);
2129   DCHECK(settings_.impl_side_painting);
2130   DCHECK(output_surface_->context_provider());
2131
2132   ReleaseTreeResources();
2133   renderer_.reset();
2134   DestroyTileManager();
2135
2136   resource_provider_->InitializeSoftware();
2137   output_surface_->ReleaseContextProvider();
2138
2139   CreateAndSetRenderer();
2140   EnforceZeroBudget(true);
2141   CreateAndSetTileManager();
2142
2143   client_->SetNeedsCommitOnImplThread();
2144 }
2145
2146 void LayerTreeHostImpl::SetViewportSize(const gfx::Size& device_viewport_size) {
2147   if (device_viewport_size == device_viewport_size_)
2148     return;
2149
2150   if (pending_tree_)
2151     active_tree_->SetViewportSizeInvalid();
2152
2153   device_viewport_size_ = device_viewport_size;
2154
2155   UpdateInnerViewportContainerSize();
2156   client_->OnCanDrawStateChanged(CanDraw());
2157   SetFullRootLayerDamage();
2158   active_tree_->set_needs_update_draw_properties();
2159 }
2160
2161 void LayerTreeHostImpl::SetTopControlsLayoutHeight(
2162     float top_controls_layout_height) {
2163   if (top_controls_layout_height_ == top_controls_layout_height)
2164     return;
2165   top_controls_layout_height_ = top_controls_layout_height;
2166
2167   UpdateInnerViewportContainerSize();
2168   SetFullRootLayerDamage();
2169 }
2170
2171 void LayerTreeHostImpl::SetOverhangUIResource(
2172     UIResourceId overhang_ui_resource_id,
2173     const gfx::Size& overhang_ui_resource_size) {
2174   overhang_ui_resource_id_ = overhang_ui_resource_id;
2175   overhang_ui_resource_size_ = overhang_ui_resource_size;
2176 }
2177
2178 void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
2179   if (device_scale_factor == device_scale_factor_)
2180     return;
2181   device_scale_factor_ = device_scale_factor;
2182
2183   SetFullRootLayerDamage();
2184 }
2185
2186 const gfx::Rect LayerTreeHostImpl::ViewportRectForTilePriority() const {
2187   if (viewport_rect_for_tile_priority_.IsEmpty())
2188     return DeviceViewport();
2189
2190   return viewport_rect_for_tile_priority_;
2191 }
2192
2193 gfx::Size LayerTreeHostImpl::DrawViewportSize() const {
2194   return DeviceViewport().size();
2195 }
2196
2197 gfx::Rect LayerTreeHostImpl::DeviceViewport() const {
2198   if (external_viewport_.IsEmpty())
2199     return gfx::Rect(device_viewport_size_);
2200
2201   return external_viewport_;
2202 }
2203
2204 gfx::Rect LayerTreeHostImpl::DeviceClip() const {
2205   if (external_clip_.IsEmpty())
2206     return DeviceViewport();
2207
2208   return external_clip_;
2209 }
2210
2211 const gfx::Transform& LayerTreeHostImpl::DrawTransform() const {
2212   return external_transform_;
2213 }
2214
2215 void LayerTreeHostImpl::DidChangeTopControlsPosition() {
2216   UpdateInnerViewportContainerSize();
2217   SetNeedsRedraw();
2218   SetNeedsAnimate();
2219   active_tree_->set_needs_update_draw_properties();
2220   SetFullRootLayerDamage();
2221 }
2222
2223 void LayerTreeHostImpl::BindToClient(InputHandlerClient* client) {
2224   DCHECK(input_handler_client_ == NULL);
2225   input_handler_client_ = client;
2226 }
2227
2228 static LayerImpl* NextScrollLayer(LayerImpl* layer) {
2229   if (LayerImpl* scroll_parent = layer->scroll_parent())
2230     return scroll_parent;
2231   return layer->parent();
2232 }
2233
2234 LayerImpl* LayerTreeHostImpl::FindScrollLayerForDeviceViewportPoint(
2235     const gfx::PointF& device_viewport_point,
2236     InputHandler::ScrollInputType type,
2237     LayerImpl* layer_impl,
2238     bool* scroll_on_main_thread,
2239     bool* optional_has_ancestor_scroll_handler) const {
2240   DCHECK(scroll_on_main_thread);
2241
2242   // Walk up the hierarchy and look for a scrollable layer.
2243   LayerImpl* potentially_scrolling_layer_impl = NULL;
2244   for (; layer_impl; layer_impl = NextScrollLayer(layer_impl)) {
2245     // The content layer can also block attempts to scroll outside the main
2246     // thread.
2247     ScrollStatus status = layer_impl->TryScroll(device_viewport_point, type);
2248     if (status == ScrollOnMainThread) {
2249       *scroll_on_main_thread = true;
2250       return NULL;
2251     }
2252
2253     LayerImpl* scroll_layer_impl = FindScrollLayerForContentLayer(layer_impl);
2254     if (!scroll_layer_impl)
2255       continue;
2256
2257     status = scroll_layer_impl->TryScroll(device_viewport_point, type);
2258     // If any layer wants to divert the scroll event to the main thread, abort.
2259     if (status == ScrollOnMainThread) {
2260       *scroll_on_main_thread = true;
2261       return NULL;
2262     }
2263
2264     if (optional_has_ancestor_scroll_handler &&
2265         scroll_layer_impl->have_scroll_event_handlers())
2266       *optional_has_ancestor_scroll_handler = true;
2267
2268     if (status == ScrollStarted && !potentially_scrolling_layer_impl)
2269       potentially_scrolling_layer_impl = scroll_layer_impl;
2270   }
2271
2272   // Falling back to the root scroll layer ensures generation of root overscroll
2273   // notifications while preventing scroll updates from being unintentionally
2274   // forwarded to the main thread.
2275   if (!potentially_scrolling_layer_impl)
2276     potentially_scrolling_layer_impl = OuterViewportScrollLayer()
2277                                            ? OuterViewportScrollLayer()
2278                                            : InnerViewportScrollLayer();
2279
2280   return potentially_scrolling_layer_impl;
2281 }
2282
2283 // Similar to LayerImpl::HasAncestor, but walks up the scroll parents.
2284 static bool HasScrollAncestor(LayerImpl* child, LayerImpl* scroll_ancestor) {
2285   DCHECK(scroll_ancestor);
2286   for (LayerImpl* ancestor = child; ancestor;
2287        ancestor = NextScrollLayer(ancestor)) {
2288     if (ancestor->scrollable())
2289       return ancestor == scroll_ancestor;
2290   }
2291   return false;
2292 }
2293
2294 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollBegin(
2295     const gfx::Point& viewport_point,
2296     InputHandler::ScrollInputType type) {
2297   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBegin");
2298
2299   if (top_controls_manager_)
2300     top_controls_manager_->ScrollBegin();
2301
2302   DCHECK(!CurrentlyScrollingLayer());
2303   ClearCurrentlyScrollingLayer();
2304
2305   gfx::PointF device_viewport_point = gfx::ScalePoint(viewport_point,
2306                                                       device_scale_factor_);
2307   LayerImpl* layer_impl =
2308       active_tree_->FindLayerThatIsHitByPoint(device_viewport_point);
2309
2310   if (layer_impl) {
2311     LayerImpl* scroll_layer_impl =
2312         active_tree_->FindFirstScrollingLayerThatIsHitByPoint(
2313             device_viewport_point);
2314     if (scroll_layer_impl && !HasScrollAncestor(layer_impl, scroll_layer_impl))
2315       return ScrollUnknown;
2316   }
2317
2318   bool scroll_on_main_thread = false;
2319   LayerImpl* scrolling_layer_impl =
2320       FindScrollLayerForDeviceViewportPoint(device_viewport_point,
2321                                             type,
2322                                             layer_impl,
2323                                             &scroll_on_main_thread,
2324                                             &scroll_affects_scroll_handler_);
2325
2326   if (scroll_on_main_thread) {
2327     UMA_HISTOGRAM_BOOLEAN("TryScroll.SlowScroll", true);
2328     return ScrollOnMainThread;
2329   }
2330
2331   if (scrolling_layer_impl) {
2332     active_tree_->SetCurrentlyScrollingLayer(scrolling_layer_impl);
2333     should_bubble_scrolls_ = (type != NonBubblingGesture);
2334     wheel_scrolling_ = (type == Wheel);
2335     client_->RenewTreePriority();
2336     UMA_HISTOGRAM_BOOLEAN("TryScroll.SlowScroll", false);
2337     return ScrollStarted;
2338   }
2339   return ScrollIgnored;
2340 }
2341
2342 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
2343     const gfx::Point& viewport_point,
2344     const gfx::Vector2dF& scroll_delta) {
2345   if (LayerImpl* layer_impl = CurrentlyScrollingLayer()) {
2346     Animation* animation =
2347         layer_impl->layer_animation_controller()->GetAnimation(
2348             Animation::ScrollOffset);
2349     if (!animation)
2350       return ScrollIgnored;
2351
2352     ScrollOffsetAnimationCurve* curve =
2353         animation->curve()->ToScrollOffsetAnimationCurve();
2354
2355     gfx::Vector2dF new_target = curve->target_value() + scroll_delta;
2356     new_target.SetToMax(gfx::Vector2dF());
2357     new_target.SetToMin(layer_impl->MaxScrollOffset());
2358
2359     curve->UpdateTarget(animation->TrimTimeToCurrentIteration(
2360                             CurrentBeginFrameArgs().frame_time),
2361                         new_target);
2362
2363     return ScrollStarted;
2364   }
2365   // ScrollAnimated is only used for wheel scrolls. We use the same bubbling
2366   // behavior as ScrollBy to determine which layer to animate, but we do not
2367   // do the Android-specific things in ScrollBy like showing top controls.
2368   InputHandler::ScrollStatus scroll_status = ScrollBegin(viewport_point, Wheel);
2369   if (scroll_status == ScrollStarted) {
2370     gfx::Vector2dF pending_delta = scroll_delta;
2371     for (LayerImpl* layer_impl = CurrentlyScrollingLayer(); layer_impl;
2372          layer_impl = layer_impl->parent()) {
2373       if (!layer_impl->scrollable())
2374         continue;
2375
2376       gfx::Vector2dF current_offset = layer_impl->TotalScrollOffset();
2377       gfx::Vector2dF target_offset = current_offset + pending_delta;
2378       target_offset.SetToMax(gfx::Vector2dF());
2379       target_offset.SetToMin(layer_impl->MaxScrollOffset());
2380       gfx::Vector2dF actual_delta = target_offset - current_offset;
2381
2382       const float kEpsilon = 0.1f;
2383       bool can_layer_scroll = (std::abs(actual_delta.x()) > kEpsilon ||
2384                                std::abs(actual_delta.y()) > kEpsilon);
2385
2386       if (!can_layer_scroll) {
2387         layer_impl->ScrollBy(actual_delta);
2388         pending_delta -= actual_delta;
2389         continue;
2390       }
2391
2392       active_tree_->SetCurrentlyScrollingLayer(layer_impl);
2393
2394       scoped_ptr<ScrollOffsetAnimationCurve> curve =
2395           ScrollOffsetAnimationCurve::Create(target_offset,
2396                                              EaseInOutTimingFunction::Create());
2397       curve->SetInitialValue(current_offset);
2398
2399       scoped_ptr<Animation> animation =
2400           Animation::Create(curve.PassAs<AnimationCurve>(),
2401                             AnimationIdProvider::NextAnimationId(),
2402                             AnimationIdProvider::NextGroupId(),
2403                             Animation::ScrollOffset);
2404       animation->set_is_impl_only(true);
2405
2406       layer_impl->layer_animation_controller()->AddAnimation(animation.Pass());
2407
2408       SetNeedsAnimate();
2409       return ScrollStarted;
2410     }
2411   }
2412   ScrollEnd();
2413   return scroll_status;
2414 }
2415
2416 gfx::Vector2dF LayerTreeHostImpl::ScrollLayerWithViewportSpaceDelta(
2417     LayerImpl* layer_impl,
2418     float scale_from_viewport_to_screen_space,
2419     const gfx::PointF& viewport_point,
2420     const gfx::Vector2dF& viewport_delta) {
2421   // Layers with non-invertible screen space transforms should not have passed
2422   // the scroll hit test in the first place.
2423   DCHECK(layer_impl->screen_space_transform().IsInvertible());
2424   gfx::Transform inverse_screen_space_transform(
2425       gfx::Transform::kSkipInitialization);
2426   bool did_invert = layer_impl->screen_space_transform().GetInverse(
2427       &inverse_screen_space_transform);
2428   // TODO(shawnsingh): With the advent of impl-side crolling for non-root
2429   // layers, we may need to explicitly handle uninvertible transforms here.
2430   DCHECK(did_invert);
2431
2432   gfx::PointF screen_space_point =
2433       gfx::ScalePoint(viewport_point, scale_from_viewport_to_screen_space);
2434
2435   gfx::Vector2dF screen_space_delta = viewport_delta;
2436   screen_space_delta.Scale(scale_from_viewport_to_screen_space);
2437
2438   // First project the scroll start and end points to local layer space to find
2439   // the scroll delta in layer coordinates.
2440   bool start_clipped, end_clipped;
2441   gfx::PointF screen_space_end_point = screen_space_point + screen_space_delta;
2442   gfx::PointF local_start_point =
2443       MathUtil::ProjectPoint(inverse_screen_space_transform,
2444                              screen_space_point,
2445                              &start_clipped);
2446   gfx::PointF local_end_point =
2447       MathUtil::ProjectPoint(inverse_screen_space_transform,
2448                              screen_space_end_point,
2449                              &end_clipped);
2450
2451   // In general scroll point coordinates should not get clipped.
2452   DCHECK(!start_clipped);
2453   DCHECK(!end_clipped);
2454   if (start_clipped || end_clipped)
2455     return gfx::Vector2dF();
2456
2457   // local_start_point and local_end_point are in content space but we want to
2458   // move them to layer space for scrolling.
2459   float width_scale = 1.f / layer_impl->contents_scale_x();
2460   float height_scale = 1.f / layer_impl->contents_scale_y();
2461   local_start_point.Scale(width_scale, height_scale);
2462   local_end_point.Scale(width_scale, height_scale);
2463
2464   // Apply the scroll delta.
2465   gfx::Vector2dF previous_delta = layer_impl->ScrollDelta();
2466   layer_impl->ScrollBy(local_end_point - local_start_point);
2467
2468   // Get the end point in the layer's content space so we can apply its
2469   // ScreenSpaceTransform.
2470   gfx::PointF actual_local_end_point = local_start_point +
2471                                        layer_impl->ScrollDelta() -
2472                                        previous_delta;
2473   gfx::PointF actual_local_content_end_point =
2474       gfx::ScalePoint(actual_local_end_point,
2475                       1.f / width_scale,
2476                       1.f / height_scale);
2477
2478   // Calculate the applied scroll delta in viewport space coordinates.
2479   gfx::PointF actual_screen_space_end_point =
2480       MathUtil::MapPoint(layer_impl->screen_space_transform(),
2481                          actual_local_content_end_point,
2482                          &end_clipped);
2483   DCHECK(!end_clipped);
2484   if (end_clipped)
2485     return gfx::Vector2dF();
2486   gfx::PointF actual_viewport_end_point =
2487       gfx::ScalePoint(actual_screen_space_end_point,
2488                       1.f / scale_from_viewport_to_screen_space);
2489   return actual_viewport_end_point - viewport_point;
2490 }
2491
2492 static gfx::Vector2dF ScrollLayerWithLocalDelta(LayerImpl* layer_impl,
2493     const gfx::Vector2dF& local_delta) {
2494   gfx::Vector2dF previous_delta(layer_impl->ScrollDelta());
2495   layer_impl->ScrollBy(local_delta);
2496   return layer_impl->ScrollDelta() - previous_delta;
2497 }
2498
2499 bool LayerTreeHostImpl::ScrollBy(const gfx::Point& viewport_point,
2500                                  const gfx::Vector2dF& scroll_delta) {
2501   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBy");
2502   if (!CurrentlyScrollingLayer())
2503     return false;
2504
2505   gfx::Vector2dF pending_delta = scroll_delta;
2506   gfx::Vector2dF unused_root_delta;
2507   bool did_scroll_x = false;
2508   bool did_scroll_y = false;
2509   bool did_scroll_top_controls = false;
2510   // TODO(wjmaclean) Should we guard against CurrentlyScrollingLayer() == 0
2511   // here?
2512   bool consume_by_top_controls =
2513       top_controls_manager_ &&
2514       (((CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
2515          CurrentlyScrollingLayer() == OuterViewportScrollLayer()) &&
2516         InnerViewportScrollLayer()->MaxScrollOffset().y() > 0) ||
2517        scroll_delta.y() < 0);
2518
2519   for (LayerImpl* layer_impl = CurrentlyScrollingLayer();
2520        layer_impl;
2521        layer_impl = layer_impl->parent()) {
2522     if (!layer_impl->scrollable())
2523       continue;
2524
2525     if (layer_impl == InnerViewportScrollLayer()) {
2526       // Only allow bubble scrolling when the scroll is in the direction to make
2527       // the top controls visible.
2528       gfx::Vector2dF applied_delta;
2529       gfx::Vector2dF excess_delta;
2530       if (consume_by_top_controls) {
2531         excess_delta = top_controls_manager_->ScrollBy(pending_delta);
2532         applied_delta = pending_delta - excess_delta;
2533         pending_delta = excess_delta;
2534         // Force updating of vertical adjust values if needed.
2535         if (applied_delta.y() != 0) {
2536           did_scroll_top_controls = true;
2537           layer_impl->ScrollbarParametersDidChange();
2538         }
2539       }
2540       // Track root layer deltas for reporting overscroll.
2541       unused_root_delta = pending_delta;
2542     }
2543
2544     gfx::Vector2dF applied_delta;
2545     // Gesture events need to be transformed from viewport coordinates to local
2546     // layer coordinates so that the scrolling contents exactly follow the
2547     // user's finger. In contrast, wheel events represent a fixed amount of
2548     // scrolling so we can just apply them directly.
2549     if (!wheel_scrolling_) {
2550       float scale_from_viewport_to_screen_space = device_scale_factor_;
2551       applied_delta =
2552           ScrollLayerWithViewportSpaceDelta(layer_impl,
2553                                             scale_from_viewport_to_screen_space,
2554                                             viewport_point, pending_delta);
2555     } else {
2556       applied_delta = ScrollLayerWithLocalDelta(layer_impl, pending_delta);
2557     }
2558
2559     const float kEpsilon = 0.1f;
2560     if (layer_impl == InnerViewportScrollLayer()) {
2561       unused_root_delta.Subtract(applied_delta);
2562       if (std::abs(unused_root_delta.x()) < kEpsilon)
2563         unused_root_delta.set_x(0.0f);
2564       if (std::abs(unused_root_delta.y()) < kEpsilon)
2565         unused_root_delta.set_y(0.0f);
2566       // Disable overscroll on axes which is impossible to scroll.
2567       if (settings_.report_overscroll_only_for_scrollable_axes) {
2568         if (std::abs(active_tree_->TotalMaxScrollOffset().x()) <= kEpsilon)
2569           unused_root_delta.set_x(0.0f);
2570         if (std::abs(active_tree_->TotalMaxScrollOffset().y()) <= kEpsilon)
2571           unused_root_delta.set_y(0.0f);
2572       }
2573     }
2574
2575     // If the layer wasn't able to move, try the next one in the hierarchy.
2576     bool did_move_layer_x = std::abs(applied_delta.x()) > kEpsilon;
2577     bool did_move_layer_y = std::abs(applied_delta.y()) > kEpsilon;
2578     did_scroll_x |= did_move_layer_x;
2579     did_scroll_y |= did_move_layer_y;
2580     if (!did_move_layer_x && !did_move_layer_y) {
2581       // Scrolls should always bubble between the outer and inner viewports
2582       if (should_bubble_scrolls_ || !did_lock_scrolling_layer_ ||
2583           layer_impl == OuterViewportScrollLayer())
2584         continue;
2585       else
2586         break;
2587     }
2588
2589     did_lock_scrolling_layer_ = true;
2590     if (!should_bubble_scrolls_) {
2591       active_tree_->SetCurrentlyScrollingLayer(layer_impl);
2592       break;
2593     }
2594
2595     // If the applied delta is within 45 degrees of the input delta, bail out to
2596     // make it easier to scroll just one layer in one direction without
2597     // affecting any of its parents.
2598     float angle_threshold = 45;
2599     if (MathUtil::SmallestAngleBetweenVectors(
2600             applied_delta, pending_delta) < angle_threshold) {
2601       pending_delta = gfx::Vector2d();
2602       break;
2603     }
2604
2605     // Allow further movement only on an axis perpendicular to the direction in
2606     // which the layer moved.
2607     gfx::Vector2dF perpendicular_axis(-applied_delta.y(), applied_delta.x());
2608     pending_delta = MathUtil::ProjectVector(pending_delta, perpendicular_axis);
2609
2610     if (gfx::ToRoundedVector2d(pending_delta).IsZero())
2611       break;
2612   }
2613
2614   bool did_scroll_content = did_scroll_x || did_scroll_y;
2615   if (did_scroll_content) {
2616     // If we are scrolling with an active scroll handler, forward latency
2617     // tracking information to the main thread so the delay introduced by the
2618     // handler is accounted for.
2619     if (scroll_affects_scroll_handler())
2620       NotifySwapPromiseMonitorsOfForwardingToMainThread();
2621     client_->SetNeedsCommitOnImplThread();
2622     SetNeedsRedraw();
2623     client_->RenewTreePriority();
2624   }
2625
2626   // Scrolling along an axis resets accumulated root overscroll for that axis.
2627   if (did_scroll_x)
2628     accumulated_root_overscroll_.set_x(0);
2629   if (did_scroll_y)
2630     accumulated_root_overscroll_.set_y(0);
2631
2632   accumulated_root_overscroll_ += unused_root_delta;
2633   bool did_overscroll = !unused_root_delta.IsZero();
2634   if (did_overscroll && input_handler_client_) {
2635     input_handler_client_->DidOverscroll(
2636         viewport_point, accumulated_root_overscroll_, unused_root_delta);
2637   }
2638
2639   return did_scroll_content || did_scroll_top_controls;
2640 }
2641
2642 // This implements scrolling by page as described here:
2643 // http://msdn.microsoft.com/en-us/library/windows/desktop/ms645601(v=vs.85).aspx#_win32_The_Mouse_Wheel
2644 // for events with WHEEL_PAGESCROLL set.
2645 bool LayerTreeHostImpl::ScrollVerticallyByPage(const gfx::Point& viewport_point,
2646                                                ScrollDirection direction) {
2647   DCHECK(wheel_scrolling_);
2648
2649   for (LayerImpl* layer_impl = CurrentlyScrollingLayer();
2650        layer_impl;
2651        layer_impl = layer_impl->parent()) {
2652     if (!layer_impl->scrollable())
2653       continue;
2654
2655     if (!layer_impl->HasScrollbar(VERTICAL))
2656       continue;
2657
2658     float height = layer_impl->clip_height();
2659
2660     // These magical values match WebKit and are designed to scroll nearly the
2661     // entire visible content height but leave a bit of overlap.
2662     float page = std::max(height * 0.875f, 1.f);
2663     if (direction == SCROLL_BACKWARD)
2664       page = -page;
2665
2666     gfx::Vector2dF delta = gfx::Vector2dF(0.f, page);
2667
2668     gfx::Vector2dF applied_delta = ScrollLayerWithLocalDelta(layer_impl, delta);
2669
2670     if (!applied_delta.IsZero()) {
2671       client_->SetNeedsCommitOnImplThread();
2672       SetNeedsRedraw();
2673       client_->RenewTreePriority();
2674       return true;
2675     }
2676
2677     active_tree_->SetCurrentlyScrollingLayer(layer_impl);
2678   }
2679
2680   return false;
2681 }
2682
2683 void LayerTreeHostImpl::SetRootLayerScrollOffsetDelegate(
2684       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) {
2685   root_layer_scroll_offset_delegate_ = root_layer_scroll_offset_delegate;
2686   active_tree_->SetRootLayerScrollOffsetDelegate(
2687       root_layer_scroll_offset_delegate_);
2688 }
2689
2690 void LayerTreeHostImpl::OnRootLayerDelegatedScrollOffsetChanged() {
2691   DCHECK(root_layer_scroll_offset_delegate_ != NULL);
2692   client_->SetNeedsCommitOnImplThread();
2693   active_tree_->set_needs_update_draw_properties();
2694 }
2695
2696 void LayerTreeHostImpl::ClearCurrentlyScrollingLayer() {
2697   active_tree_->ClearCurrentlyScrollingLayer();
2698   did_lock_scrolling_layer_ = false;
2699   scroll_affects_scroll_handler_ = false;
2700   accumulated_root_overscroll_ = gfx::Vector2dF();
2701 }
2702
2703 void LayerTreeHostImpl::ScrollEnd() {
2704   if (top_controls_manager_)
2705     top_controls_manager_->ScrollEnd();
2706   ClearCurrentlyScrollingLayer();
2707 }
2708
2709 InputHandler::ScrollStatus LayerTreeHostImpl::FlingScrollBegin() {
2710   if (!active_tree_->CurrentlyScrollingLayer())
2711     return ScrollIgnored;
2712
2713   if (settings_.ignore_root_layer_flings &&
2714       (active_tree_->CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
2715        active_tree_->CurrentlyScrollingLayer() == OuterViewportScrollLayer())) {
2716     ClearCurrentlyScrollingLayer();
2717     return ScrollIgnored;
2718   }
2719
2720   if (!wheel_scrolling_) {
2721     // Allow the fling to lock to the first layer that moves after the initial
2722     // fling |ScrollBy()| event.
2723     did_lock_scrolling_layer_ = false;
2724     should_bubble_scrolls_ = false;
2725   }
2726
2727   return ScrollStarted;
2728 }
2729
2730 float LayerTreeHostImpl::DeviceSpaceDistanceToLayer(
2731     const gfx::PointF& device_viewport_point,
2732     LayerImpl* layer_impl) {
2733   if (!layer_impl)
2734     return std::numeric_limits<float>::max();
2735
2736   gfx::Rect layer_impl_bounds(
2737       layer_impl->content_bounds());
2738
2739   gfx::RectF device_viewport_layer_impl_bounds = MathUtil::MapClippedRect(
2740       layer_impl->screen_space_transform(),
2741       layer_impl_bounds);
2742
2743   return device_viewport_layer_impl_bounds.ManhattanDistanceToPoint(
2744       device_viewport_point);
2745 }
2746
2747 void LayerTreeHostImpl::MouseMoveAt(const gfx::Point& viewport_point) {
2748   gfx::PointF device_viewport_point = gfx::ScalePoint(viewport_point,
2749                                                       device_scale_factor_);
2750   LayerImpl* layer_impl =
2751       active_tree_->FindLayerThatIsHitByPoint(device_viewport_point);
2752   if (HandleMouseOverScrollbar(layer_impl, device_viewport_point))
2753     return;
2754
2755   if (scroll_layer_id_when_mouse_over_scrollbar_) {
2756     LayerImpl* scroll_layer_impl = active_tree_->LayerById(
2757         scroll_layer_id_when_mouse_over_scrollbar_);
2758
2759     // The check for a null scroll_layer_impl below was added to see if it will
2760     // eliminate the crashes described in http://crbug.com/326635.
2761     // TODO(wjmaclean) Add a unit test if this fixes the crashes.
2762     ScrollbarAnimationController* animation_controller =
2763         scroll_layer_impl ? scroll_layer_impl->scrollbar_animation_controller()
2764                           : NULL;
2765     if (animation_controller)
2766       animation_controller->DidMouseMoveOffScrollbar();
2767     scroll_layer_id_when_mouse_over_scrollbar_ = 0;
2768   }
2769
2770   bool scroll_on_main_thread = false;
2771   LayerImpl* scroll_layer_impl =
2772       FindScrollLayerForDeviceViewportPoint(device_viewport_point,
2773                                             InputHandler::Gesture,
2774                                             layer_impl,
2775                                             &scroll_on_main_thread,
2776                                             NULL);
2777   if (scroll_on_main_thread || !scroll_layer_impl)
2778     return;
2779
2780   ScrollbarAnimationController* animation_controller =
2781       scroll_layer_impl->scrollbar_animation_controller();
2782   if (!animation_controller)
2783     return;
2784
2785   // TODO(wjmaclean) Is it ok to choose distance from more than two scrollbars?
2786   float distance_to_scrollbar = std::numeric_limits<float>::max();
2787   for (LayerImpl::ScrollbarSet::iterator it =
2788            scroll_layer_impl->scrollbars()->begin();
2789        it != scroll_layer_impl->scrollbars()->end();
2790        ++it)
2791     distance_to_scrollbar =
2792         std::min(distance_to_scrollbar,
2793                  DeviceSpaceDistanceToLayer(device_viewport_point, *it));
2794
2795   animation_controller->DidMouseMoveNear(distance_to_scrollbar /
2796                                          device_scale_factor_);
2797 }
2798
2799 bool LayerTreeHostImpl::HandleMouseOverScrollbar(LayerImpl* layer_impl,
2800     const gfx::PointF& device_viewport_point) {
2801   if (layer_impl && layer_impl->ToScrollbarLayer()) {
2802     int scroll_layer_id = layer_impl->ToScrollbarLayer()->ScrollLayerId();
2803     layer_impl = active_tree_->LayerById(scroll_layer_id);
2804     if (layer_impl && layer_impl->scrollbar_animation_controller()) {
2805       scroll_layer_id_when_mouse_over_scrollbar_ = scroll_layer_id;
2806       layer_impl->scrollbar_animation_controller()->DidMouseMoveNear(0);
2807     } else {
2808       scroll_layer_id_when_mouse_over_scrollbar_ = 0;
2809     }
2810
2811     return true;
2812   }
2813
2814   return false;
2815 }
2816
2817 void LayerTreeHostImpl::PinchGestureBegin() {
2818   pinch_gesture_active_ = true;
2819   previous_pinch_anchor_ = gfx::Point();
2820   client_->RenewTreePriority();
2821   pinch_gesture_end_should_clear_scrolling_layer_ = !CurrentlyScrollingLayer();
2822   if (active_tree_->OuterViewportScrollLayer()) {
2823     active_tree_->SetCurrentlyScrollingLayer(
2824         active_tree_->OuterViewportScrollLayer());
2825   } else {
2826     active_tree_->SetCurrentlyScrollingLayer(
2827         active_tree_->InnerViewportScrollLayer());
2828   }
2829   if (top_controls_manager_)
2830     top_controls_manager_->PinchBegin();
2831 }
2832
2833 void LayerTreeHostImpl::PinchGestureUpdate(float magnify_delta,
2834                                            const gfx::Point& anchor) {
2835   if (!InnerViewportScrollLayer())
2836     return;
2837
2838   TRACE_EVENT0("cc", "LayerTreeHostImpl::PinchGestureUpdate");
2839
2840   // For a moment the scroll offset ends up being outside of the max range. This
2841   // confuses the delegate so we switch it off till after we're done processing
2842   // the pinch update.
2843   active_tree_->SetRootLayerScrollOffsetDelegate(NULL);
2844
2845   // Keep the center-of-pinch anchor specified by (x, y) in a stable
2846   // position over the course of the magnify.
2847   float page_scale_delta = active_tree_->page_scale_delta();
2848   gfx::PointF previous_scale_anchor =
2849       gfx::ScalePoint(anchor, 1.f / page_scale_delta);
2850   active_tree_->SetPageScaleDelta(page_scale_delta * magnify_delta);
2851   page_scale_delta = active_tree_->page_scale_delta();
2852   gfx::PointF new_scale_anchor =
2853       gfx::ScalePoint(anchor, 1.f / page_scale_delta);
2854   gfx::Vector2dF move = previous_scale_anchor - new_scale_anchor;
2855
2856   previous_pinch_anchor_ = anchor;
2857
2858   move.Scale(1 / active_tree_->page_scale_factor());
2859   // If clamping the inner viewport scroll offset causes a change, it should
2860   // be accounted for from the intended move.
2861   move -= InnerViewportScrollLayer()->ClampScrollToMaxScrollOffset();
2862
2863   // We manually manage the bubbling behaviour here as it is different to that
2864   // implemented in LayerTreeHostImpl::ScrollBy(). Specifically:
2865   // 1) we want to explicit limit the bubbling to the outer/inner viewports,
2866   // 2) we don't want the directional limitations on the unused parts that
2867   //    ScrollBy() implements, and
2868   // 3) pinching should not engage the top controls manager.
2869   gfx::Vector2dF unused = OuterViewportScrollLayer()
2870                               ? OuterViewportScrollLayer()->ScrollBy(move)
2871                               : move;
2872
2873   if (!unused.IsZero()) {
2874     InnerViewportScrollLayer()->ScrollBy(unused);
2875     InnerViewportScrollLayer()->ClampScrollToMaxScrollOffset();
2876   }
2877
2878   active_tree_->SetRootLayerScrollOffsetDelegate(
2879       root_layer_scroll_offset_delegate_);
2880
2881   client_->SetNeedsCommitOnImplThread();
2882   SetNeedsRedraw();
2883   client_->RenewTreePriority();
2884 }
2885
2886 void LayerTreeHostImpl::PinchGestureEnd() {
2887   pinch_gesture_active_ = false;
2888   if (pinch_gesture_end_should_clear_scrolling_layer_) {
2889     pinch_gesture_end_should_clear_scrolling_layer_ = false;
2890     ClearCurrentlyScrollingLayer();
2891   }
2892   if (top_controls_manager_)
2893     top_controls_manager_->PinchEnd();
2894   client_->SetNeedsCommitOnImplThread();
2895 }
2896
2897 static void CollectScrollDeltas(ScrollAndScaleSet* scroll_info,
2898                                 LayerImpl* layer_impl) {
2899   if (!layer_impl)
2900     return;
2901
2902   gfx::Vector2d scroll_delta =
2903       gfx::ToFlooredVector2d(layer_impl->ScrollDelta());
2904   if (!scroll_delta.IsZero()) {
2905     LayerTreeHostCommon::ScrollUpdateInfo scroll;
2906     scroll.layer_id = layer_impl->id();
2907     scroll.scroll_delta = scroll_delta;
2908     scroll_info->scrolls.push_back(scroll);
2909     layer_impl->SetSentScrollDelta(scroll_delta);
2910   }
2911
2912   for (size_t i = 0; i < layer_impl->children().size(); ++i)
2913     CollectScrollDeltas(scroll_info, layer_impl->children()[i]);
2914 }
2915
2916 scoped_ptr<ScrollAndScaleSet> LayerTreeHostImpl::ProcessScrollDeltas() {
2917   scoped_ptr<ScrollAndScaleSet> scroll_info(new ScrollAndScaleSet());
2918
2919   CollectScrollDeltas(scroll_info.get(), active_tree_->root_layer());
2920   scroll_info->page_scale_delta = active_tree_->page_scale_delta();
2921   active_tree_->set_sent_page_scale_delta(scroll_info->page_scale_delta);
2922   scroll_info->swap_promises.swap(swap_promises_for_main_thread_scroll_update_);
2923
2924   return scroll_info.Pass();
2925 }
2926
2927 void LayerTreeHostImpl::SetFullRootLayerDamage() {
2928   SetViewportDamage(gfx::Rect(DrawViewportSize()));
2929 }
2930
2931 void LayerTreeHostImpl::ScrollViewportBy(gfx::Vector2dF scroll_delta) {
2932   DCHECK(InnerViewportScrollLayer());
2933   LayerImpl* scroll_layer = OuterViewportScrollLayer()
2934                                 ? OuterViewportScrollLayer()
2935                                 : InnerViewportScrollLayer();
2936
2937   gfx::Vector2dF unused_delta = scroll_layer->ScrollBy(scroll_delta);
2938
2939   if (!unused_delta.IsZero() && (scroll_layer == OuterViewportScrollLayer()))
2940     InnerViewportScrollLayer()->ScrollBy(unused_delta);
2941 }
2942
2943 void LayerTreeHostImpl::AnimatePageScale(base::TimeTicks monotonic_time) {
2944   if (!page_scale_animation_)
2945     return;
2946
2947   gfx::Vector2dF scroll_total = active_tree_->TotalScrollOffset();
2948
2949   if (!page_scale_animation_->IsAnimationStarted())
2950     page_scale_animation_->StartAnimation(monotonic_time);
2951
2952   active_tree_->SetPageScaleDelta(
2953       page_scale_animation_->PageScaleFactorAtTime(monotonic_time) /
2954       active_tree_->page_scale_factor());
2955   gfx::Vector2dF next_scroll =
2956       page_scale_animation_->ScrollOffsetAtTime(monotonic_time);
2957
2958   ScrollViewportBy(next_scroll - scroll_total);
2959   SetNeedsRedraw();
2960
2961   if (page_scale_animation_->IsAnimationCompleteAtTime(monotonic_time)) {
2962     page_scale_animation_.reset();
2963     client_->SetNeedsCommitOnImplThread();
2964     client_->RenewTreePriority();
2965   } else {
2966     SetNeedsAnimate();
2967   }
2968 }
2969
2970 void LayerTreeHostImpl::AnimateTopControls(base::TimeTicks time) {
2971   if (!top_controls_manager_ || !top_controls_manager_->animation())
2972     return;
2973
2974   gfx::Vector2dF scroll = top_controls_manager_->Animate(time);
2975
2976   if (top_controls_manager_->animation())
2977     SetNeedsAnimate();
2978
2979   if (active_tree_->TotalScrollOffset().y() == 0.f)
2980     return;
2981
2982   if (scroll.IsZero())
2983     return;
2984
2985   ScrollViewportBy(gfx::ScaleVector2d(
2986       scroll, 1.f / active_tree_->total_page_scale_factor()));
2987   SetNeedsRedraw();
2988   client_->SetNeedsCommitOnImplThread();
2989   client_->RenewTreePriority();
2990 }
2991
2992 void LayerTreeHostImpl::AnimateLayers(base::TimeTicks monotonic_time) {
2993   if (!settings_.accelerated_animation_enabled ||
2994       !needs_animate_layers() ||
2995       !active_tree_->root_layer())
2996     return;
2997
2998   TRACE_EVENT0("cc", "LayerTreeHostImpl::AnimateLayers");
2999   AnimationRegistrar::AnimationControllerMap copy =
3000       animation_registrar_->active_animation_controllers();
3001   for (AnimationRegistrar::AnimationControllerMap::iterator iter = copy.begin();
3002        iter != copy.end();
3003        ++iter)
3004     (*iter).second->Animate(monotonic_time);
3005
3006   SetNeedsAnimate();
3007 }
3008
3009 void LayerTreeHostImpl::UpdateAnimationState(bool start_ready_animations) {
3010   if (!settings_.accelerated_animation_enabled ||
3011       !needs_animate_layers() ||
3012       !active_tree_->root_layer())
3013     return;
3014
3015   TRACE_EVENT0("cc", "LayerTreeHostImpl::UpdateAnimationState");
3016   scoped_ptr<AnimationEventsVector> events =
3017       make_scoped_ptr(new AnimationEventsVector);
3018   AnimationRegistrar::AnimationControllerMap copy =
3019       animation_registrar_->active_animation_controllers();
3020   for (AnimationRegistrar::AnimationControllerMap::iterator iter = copy.begin();
3021        iter != copy.end();
3022        ++iter)
3023     (*iter).second->UpdateState(start_ready_animations, events.get());
3024
3025   if (!events->empty()) {
3026     client_->PostAnimationEventsToMainThreadOnImplThread(events.Pass());
3027   }
3028
3029   SetNeedsAnimate();
3030 }
3031
3032 void LayerTreeHostImpl::ActivateAnimations() {
3033   if (!settings_.accelerated_animation_enabled || !needs_animate_layers() ||
3034       !active_tree_->root_layer())
3035     return;
3036
3037   TRACE_EVENT0("cc", "LayerTreeHostImpl::ActivateAnimations");
3038   AnimationRegistrar::AnimationControllerMap copy =
3039       animation_registrar_->active_animation_controllers();
3040   for (AnimationRegistrar::AnimationControllerMap::iterator iter = copy.begin();
3041        iter != copy.end();
3042        ++iter)
3043     (*iter).second->ActivateAnimations();
3044 }
3045
3046 base::TimeDelta LayerTreeHostImpl::LowFrequencyAnimationInterval() const {
3047   return base::TimeDelta::FromSeconds(1);
3048 }
3049
3050 std::string LayerTreeHostImpl::LayerTreeAsJson() const {
3051   std::string str;
3052   if (active_tree_->root_layer()) {
3053     scoped_ptr<base::Value> json(active_tree_->root_layer()->LayerTreeAsJson());
3054     base::JSONWriter::WriteWithOptions(
3055         json.get(), base::JSONWriter::OPTIONS_PRETTY_PRINT, &str);
3056   }
3057   return str;
3058 }
3059
3060 int LayerTreeHostImpl::SourceAnimationFrameNumber() const {
3061   return fps_counter_->current_frame_number();
3062 }
3063
3064 void LayerTreeHostImpl::AnimateScrollbars(base::TimeTicks time) {
3065   AnimateScrollbarsRecursive(active_tree_->root_layer(), time);
3066 }
3067
3068 void LayerTreeHostImpl::AnimateScrollbarsRecursive(LayerImpl* layer,
3069                                                    base::TimeTicks time) {
3070   if (!layer)
3071     return;
3072
3073   ScrollbarAnimationController* scrollbar_controller =
3074       layer->scrollbar_animation_controller();
3075   if (scrollbar_controller)
3076     scrollbar_controller->Animate(time);
3077
3078   for (size_t i = 0; i < layer->children().size(); ++i)
3079     AnimateScrollbarsRecursive(layer->children()[i], time);
3080 }
3081
3082 void LayerTreeHostImpl::PostDelayedScrollbarFade(
3083     const base::Closure& start_fade,
3084     base::TimeDelta delay) {
3085   client_->PostDelayedScrollbarFadeOnImplThread(start_fade, delay);
3086 }
3087
3088 void LayerTreeHostImpl::SetNeedsScrollbarAnimationFrame() {
3089   TRACE_EVENT_INSTANT0(
3090       "cc",
3091       "LayerTreeHostImpl::SetNeedsRedraw due to scrollbar fade",
3092       TRACE_EVENT_SCOPE_THREAD);
3093   SetNeedsAnimate();
3094 }
3095
3096 void LayerTreeHostImpl::SetTreePriority(TreePriority priority) {
3097   if (!tile_manager_)
3098     return;
3099
3100   if (global_tile_state_.tree_priority == priority)
3101     return;
3102   global_tile_state_.tree_priority = priority;
3103   DidModifyTilePriorities();
3104 }
3105
3106 void LayerTreeHostImpl::UpdateCurrentBeginFrameArgs(
3107     const BeginFrameArgs& args) {
3108   DCHECK(!current_begin_frame_args_.IsValid());
3109   current_begin_frame_args_ = args;
3110   // TODO(skyostil): Stop overriding the frame time once the usage of frame
3111   // timing is unified.
3112   current_begin_frame_args_.frame_time = gfx::FrameTime::Now();
3113 }
3114
3115 void LayerTreeHostImpl::ResetCurrentBeginFrameArgsForNextFrame() {
3116   current_begin_frame_args_ = BeginFrameArgs();
3117 }
3118
3119 BeginFrameArgs LayerTreeHostImpl::CurrentBeginFrameArgs() const {
3120   // Try to use the current frame time to keep animations non-jittery.  But if
3121   // we're not in a frame (because this is during an input event or a delayed
3122   // task), fall back to physical time.  This should still be monotonic.
3123   if (current_begin_frame_args_.IsValid())
3124     return current_begin_frame_args_;
3125   return BeginFrameArgs::Create(gfx::FrameTime::Now(),
3126                                 base::TimeTicks(),
3127                                 BeginFrameArgs::DefaultInterval());
3128 }
3129
3130 scoped_refptr<base::debug::ConvertableToTraceFormat>
3131 LayerTreeHostImpl::AsValue() const {
3132   return AsValueWithFrame(NULL);
3133 }
3134
3135 scoped_refptr<base::debug::ConvertableToTraceFormat>
3136 LayerTreeHostImpl::AsValueWithFrame(FrameData* frame) const {
3137   scoped_refptr<base::debug::TracedValue> state =
3138       new base::debug::TracedValue();
3139   AsValueWithFrameInto(frame, state.get());
3140   return state;
3141 }
3142
3143 void LayerTreeHostImpl::AsValueWithFrameInto(
3144     FrameData* frame,
3145     base::debug::TracedValue* state) const {
3146   if (this->pending_tree_) {
3147     state->BeginDictionary("activation_state");
3148     ActivationStateAsValueInto(state);
3149     state->EndDictionary();
3150   }
3151   state->BeginDictionary("device_viewport_size");
3152   MathUtil::AddToTracedValue(device_viewport_size_, state);
3153   state->EndDictionary();
3154
3155   std::set<const Tile*> tiles;
3156   active_tree_->GetAllTilesForTracing(&tiles);
3157   if (pending_tree_)
3158     pending_tree_->GetAllTilesForTracing(&tiles);
3159
3160   state->BeginArray("active_tiles");
3161   for (std::set<const Tile*>::const_iterator it = tiles.begin();
3162        it != tiles.end();
3163        ++it) {
3164     const Tile* tile = *it;
3165
3166     state->BeginDictionary();
3167     tile->AsValueInto(state);
3168     state->EndDictionary();
3169   }
3170   state->EndArray();
3171
3172   if (tile_manager_) {
3173     state->BeginDictionary("tile_manager_basic_state");
3174     tile_manager_->BasicStateAsValueInto(state);
3175     state->EndDictionary();
3176   }
3177   state->BeginDictionary("active_tree");
3178   active_tree_->AsValueInto(state);
3179   state->EndDictionary();
3180   if (pending_tree_) {
3181     state->BeginDictionary("pending_tree");
3182     pending_tree_->AsValueInto(state);
3183     state->EndDictionary();
3184   }
3185   if (frame) {
3186     state->BeginDictionary("frame");
3187     frame->AsValueInto(state);
3188     state->EndDictionary();
3189   }
3190 }
3191
3192 scoped_refptr<base::debug::ConvertableToTraceFormat>
3193 LayerTreeHostImpl::ActivationStateAsValue() const {
3194   scoped_refptr<base::debug::TracedValue> state =
3195       new base::debug::TracedValue();
3196   ActivationStateAsValueInto(state.get());
3197   return state;
3198 }
3199
3200 void LayerTreeHostImpl::ActivationStateAsValueInto(
3201     base::debug::TracedValue* state) const {
3202   TracedValue::SetIDRef(this, state, "lthi");
3203   if (tile_manager_) {
3204     state->BeginDictionary("tile_manager");
3205     tile_manager_->BasicStateAsValueInto(state);
3206     state->EndDictionary();
3207   }
3208 }
3209
3210 void LayerTreeHostImpl::SetDebugState(
3211     const LayerTreeDebugState& new_debug_state) {
3212   if (LayerTreeDebugState::Equal(debug_state_, new_debug_state))
3213     return;
3214   if (debug_state_.continuous_painting != new_debug_state.continuous_painting)
3215     paint_time_counter_->ClearHistory();
3216
3217   debug_state_ = new_debug_state;
3218   UpdateTileManagerMemoryPolicy(ActualManagedMemoryPolicy());
3219   SetFullRootLayerDamage();
3220 }
3221
3222 void LayerTreeHostImpl::CreateUIResource(UIResourceId uid,
3223                                          const UIResourceBitmap& bitmap) {
3224   DCHECK_GT(uid, 0);
3225
3226   GLint wrap_mode = 0;
3227   switch (bitmap.GetWrapMode()) {
3228     case UIResourceBitmap::CLAMP_TO_EDGE:
3229       wrap_mode = GL_CLAMP_TO_EDGE;
3230       break;
3231     case UIResourceBitmap::REPEAT:
3232       wrap_mode = GL_REPEAT;
3233       break;
3234   }
3235
3236   // Allow for multiple creation requests with the same UIResourceId.  The
3237   // previous resource is simply deleted.
3238   ResourceProvider::ResourceId id = ResourceIdForUIResource(uid);
3239   if (id)
3240     DeleteUIResource(uid);
3241
3242   ResourceFormat format = resource_provider_->best_texture_format();
3243   switch (bitmap.GetFormat()) {
3244     case UIResourceBitmap::RGBA8:
3245       break;
3246     case UIResourceBitmap::ALPHA_8:
3247       format = ALPHA_8;
3248       break;
3249     case UIResourceBitmap::ETC1:
3250       format = ETC1;
3251       break;
3252   }
3253   id =
3254       resource_provider_->CreateResource(bitmap.GetSize(),
3255                                          wrap_mode,
3256                                          ResourceProvider::TextureHintImmutable,
3257                                          format);
3258
3259   UIResourceData data;
3260   data.resource_id = id;
3261   data.size = bitmap.GetSize();
3262   data.opaque = bitmap.GetOpaque();
3263
3264   ui_resource_map_[uid] = data;
3265
3266   AutoLockUIResourceBitmap bitmap_lock(bitmap);
3267   resource_provider_->SetPixels(id,
3268                                 bitmap_lock.GetPixels(),
3269                                 gfx::Rect(bitmap.GetSize()),
3270                                 gfx::Rect(bitmap.GetSize()),
3271                                 gfx::Vector2d(0, 0));
3272   MarkUIResourceNotEvicted(uid);
3273 }
3274
3275 void LayerTreeHostImpl::DeleteUIResource(UIResourceId uid) {
3276   ResourceProvider::ResourceId id = ResourceIdForUIResource(uid);
3277   if (id) {
3278     resource_provider_->DeleteResource(id);
3279     ui_resource_map_.erase(uid);
3280   }
3281   MarkUIResourceNotEvicted(uid);
3282 }
3283
3284 void LayerTreeHostImpl::EvictAllUIResources() {
3285   if (ui_resource_map_.empty())
3286     return;
3287
3288   for (UIResourceMap::const_iterator iter = ui_resource_map_.begin();
3289       iter != ui_resource_map_.end();
3290       ++iter) {
3291     evicted_ui_resources_.insert(iter->first);
3292     resource_provider_->DeleteResource(iter->second.resource_id);
3293   }
3294   ui_resource_map_.clear();
3295
3296   client_->SetNeedsCommitOnImplThread();
3297   client_->OnCanDrawStateChanged(CanDraw());
3298   client_->RenewTreePriority();
3299 }
3300
3301 ResourceProvider::ResourceId LayerTreeHostImpl::ResourceIdForUIResource(
3302     UIResourceId uid) const {
3303   UIResourceMap::const_iterator iter = ui_resource_map_.find(uid);
3304   if (iter != ui_resource_map_.end())
3305     return iter->second.resource_id;
3306   return 0;
3307 }
3308
3309 bool LayerTreeHostImpl::IsUIResourceOpaque(UIResourceId uid) const {
3310   UIResourceMap::const_iterator iter = ui_resource_map_.find(uid);
3311   DCHECK(iter != ui_resource_map_.end());
3312   return iter->second.opaque;
3313 }
3314
3315 bool LayerTreeHostImpl::EvictedUIResourcesExist() const {
3316   return !evicted_ui_resources_.empty();
3317 }
3318
3319 void LayerTreeHostImpl::MarkUIResourceNotEvicted(UIResourceId uid) {
3320   std::set<UIResourceId>::iterator found_in_evicted =
3321       evicted_ui_resources_.find(uid);
3322   if (found_in_evicted == evicted_ui_resources_.end())
3323     return;
3324   evicted_ui_resources_.erase(found_in_evicted);
3325   if (evicted_ui_resources_.empty())
3326     client_->OnCanDrawStateChanged(CanDraw());
3327 }
3328
3329 void LayerTreeHostImpl::ScheduleMicroBenchmark(
3330     scoped_ptr<MicroBenchmarkImpl> benchmark) {
3331   micro_benchmark_controller_.ScheduleRun(benchmark.Pass());
3332 }
3333
3334 void LayerTreeHostImpl::InsertSwapPromiseMonitor(SwapPromiseMonitor* monitor) {
3335   swap_promise_monitor_.insert(monitor);
3336 }
3337
3338 void LayerTreeHostImpl::RemoveSwapPromiseMonitor(SwapPromiseMonitor* monitor) {
3339   swap_promise_monitor_.erase(monitor);
3340 }
3341
3342 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
3343   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
3344   for (; it != swap_promise_monitor_.end(); it++)
3345     (*it)->OnSetNeedsRedrawOnImpl();
3346 }
3347
3348 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfForwardingToMainThread() {
3349   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
3350   for (; it != swap_promise_monitor_.end(); it++)
3351     (*it)->OnForwardScrollUpdateToMainThreadOnImpl();
3352 }
3353
3354 void LayerTreeHostImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
3355   DCHECK(std::find(picture_layers_.begin(), picture_layers_.end(), layer) ==
3356          picture_layers_.end());
3357   picture_layers_.push_back(layer);
3358 }
3359
3360 void LayerTreeHostImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
3361   std::vector<PictureLayerImpl*>::iterator it =
3362       std::find(picture_layers_.begin(), picture_layers_.end(), layer);
3363   DCHECK(it != picture_layers_.end());
3364   picture_layers_.erase(it);
3365 }
3366
3367 }  // namespace cc