content/renderer/render_thread_impl.h

   1 // Copyright (c) 2012 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 #ifndef CONTENT_RENDERER_RENDER_THREAD_IMPL_H_
   6 #define CONTENT_RENDERER_RENDER_THREAD_IMPL_H_
   7
   8 #include <set>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "base/memory/memory_pressure_listener.h"
  13 #include "base/metrics/user_metrics_action.h"
  14 #include "base/observer_list.h"
  15 #include "base/strings/string16.h"
  16 #include "base/threading/thread_checker.h"
  17 #include "base/timer/timer.h"
  18 #include "build/build_config.h"
  19 #include "content/child/child_thread.h"
  20 #include "content/common/content_export.h"
  21 #include "content/common/gpu/client/gpu_channel_host.h"
  22 #include "content/public/renderer/render_thread.h"
  23 #include "ui/gfx/native_widget_types.h"
  24
  25 #if defined(OS_MACOSX)
  26 #include "third_party/WebKit/public/web/mac/WebScrollbarTheme.h"
  27 #endif
  28
  29 class GrContext;
  30 class SkBitmap;
  31 struct ViewMsg_New_Params;
  32 struct WorkerProcessMsg_CreateWorker_Params;
  33
  34 namespace blink {
  35 class WebGamepads;
  36 class WebGamepadListener;
  37 class WebGraphicsContext3D;
  38 class WebMediaStreamCenter;
  39 class WebMediaStreamCenterClient;
  40 }
  41
  42 namespace base {
  43 class MessageLoopProxy;
  44 class Thread;
  45 }
  46
  47 namespace cc {
  48 class ContextProvider;
  49 }
  50
  51 namespace IPC {
  52 class ForwardingMessageFilter;
  53 class MessageFilter;
  54 }
  55
  56 namespace media {
  57 class AudioHardwareConfig;
  58 class GpuVideoAcceleratorFactories;
  59 }
  60
  61 namespace v8 {
  62 class Extension;
  63 }
  64
  65 namespace webkit {
  66 namespace gpu {
  67 class ContextProviderWebContext;
  68 class GrContextForWebGraphicsContext3D;
  69 }
  70 }
  71
  72 namespace content {
  73
  74 class AppCacheDispatcher;
  75 class AudioInputMessageFilter;
  76 class AudioMessageFilter;
  77 class AudioRendererMixerManager;
  78 class ContextProviderCommandBuffer;
  79 class DBMessageFilter;
  80 class DevToolsAgentFilter;
  81 class DomStorageDispatcher;
  82 class EmbeddedWorkerDispatcher;
  83 class GamepadSharedMemoryReader;
  84 class GpuChannelHost;
  85 class IndexedDBDispatcher;
  86 class InputEventFilter;
  87 class InputHandlerManager;
  88 class MediaStreamCenter;
  89 class PeerConnectionDependencyFactory;
  90 class MidiMessageFilter;
  91 class P2PSocketDispatcher;
  92 class PeerConnectionTracker;
  93 class RendererDemuxerAndroid;
  94 class RendererWebKitPlatformSupportImpl;
  95 class RenderProcessObserver;
  96 class VideoCaptureImplManager;
  97 class WebGraphicsContext3DCommandBufferImpl;
  98 class WebRTCIdentityService;
  99
 100 // The RenderThreadImpl class represents a background thread where RenderView
 101 // instances live.  The RenderThread supports an API that is used by its
 102 // consumer to talk indirectly to the RenderViews and supporting objects.
 103 // Likewise, it provides an API for the RenderViews to talk back to the main
 104 // process (i.e., their corresponding WebContentsImpl).
 105 //
 106 // Most of the communication occurs in the form of IPC messages.  They are
 107 // routed to the RenderThread according to the routing IDs of the messages.
 108 // The routing IDs correspond to RenderView instances.
 109 class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
 110                                         public ChildThread,
 111                                         public GpuChannelHostFactory {
 112  public:
 113   static RenderThreadImpl* current();
 114
 115   RenderThreadImpl();
 116   // Constructor that's used when running in single process mode.
 117   explicit RenderThreadImpl(const std::string& channel_name);
 118   virtual ~RenderThreadImpl();
 119   virtual void Shutdown() OVERRIDE;
 120
 121   // When initializing WebKit, ensure that any schemes needed for the content
 122   // module are registered properly.  Static to allow sharing with tests.
 123   static void RegisterSchemes();
 124
 125   // Notify V8 that the date/time configuration of the system might have
 126   // changed.
 127   static void NotifyTimezoneChange();
 128
 129   // RenderThread implementation:
 130   virtual bool Send(IPC::Message* msg) OVERRIDE;
 131   virtual base::MessageLoop* GetMessageLoop() OVERRIDE;
 132   virtual IPC::SyncChannel* GetChannel() OVERRIDE;
 133   virtual std::string GetLocale() OVERRIDE;
 134   virtual IPC::SyncMessageFilter* GetSyncMessageFilter() OVERRIDE;
 135   virtual scoped_refptr<base::MessageLoopProxy> GetIOMessageLoopProxy()
 136       OVERRIDE;
 137   virtual void AddRoute(int32 routing_id, IPC::Listener* listener) OVERRIDE;
 138   virtual void RemoveRoute(int32 routing_id) OVERRIDE;
 139   virtual int GenerateRoutingID() OVERRIDE;
 140   virtual void AddFilter(IPC::MessageFilter* filter) OVERRIDE;
 141   virtual void RemoveFilter(IPC::MessageFilter* filter) OVERRIDE;
 142   virtual void AddObserver(RenderProcessObserver* observer) OVERRIDE;
 143   virtual void RemoveObserver(RenderProcessObserver* observer) OVERRIDE;
 144   virtual void SetResourceDispatcherDelegate(
 145       ResourceDispatcherDelegate* delegate) OVERRIDE;
 146   virtual void EnsureWebKitInitialized() OVERRIDE;
 147   virtual void RecordAction(const base::UserMetricsAction& action) OVERRIDE;
 148   virtual void RecordComputedAction(const std::string& action) OVERRIDE;
 149   virtual scoped_ptr<base::SharedMemory> HostAllocateSharedMemoryBuffer(
 150       size_t buffer_size) OVERRIDE;
 151   virtual void RegisterExtension(v8::Extension* extension) OVERRIDE;
 152   virtual void ScheduleIdleHandler(int64 initial_delay_ms) OVERRIDE;
 153   virtual void IdleHandler() OVERRIDE;
 154   virtual int64 GetIdleNotificationDelayInMs() const OVERRIDE;
 155   virtual void SetIdleNotificationDelayInMs(
 156       int64 idle_notification_delay_in_ms) OVERRIDE;
 157   virtual void UpdateHistograms(int sequence_number) OVERRIDE;
 158   virtual int PostTaskToAllWebWorkers(const base::Closure& closure) OVERRIDE;
 159   virtual bool ResolveProxy(const GURL& url, std::string* proxy_list) OVERRIDE;
 160   virtual base::WaitableEvent* GetShutdownEvent() OVERRIDE;
 161 #if defined(OS_WIN)
 162   virtual void PreCacheFont(const LOGFONT& log_font) OVERRIDE;
 163   virtual void ReleaseCachedFonts() OVERRIDE;
 164 #endif
 165
 166   // Synchronously establish a channel to the GPU plugin if not previously
 167   // established or if it has been lost (for example if the GPU plugin crashed).
 168   // If there is a pending asynchronous request, it will be completed by the
 169   // time this routine returns.
 170   GpuChannelHost* EstablishGpuChannelSync(CauseForGpuLaunch);
 171
 172
 173   // These methods modify how the next message is sent.  Normally, when sending
 174   // a synchronous message that runs a nested message loop, we need to suspend
 175   // callbacks into WebKit.  This involves disabling timers and deferring
 176   // resource loads.  However, there are exceptions when we need to customize
 177   // the behavior.
 178   void DoNotSuspendWebKitSharedTimer();
 179   void DoNotNotifyWebKitOfModalLoop();
 180
 181   // True if we are running layout tests. This currently disables forwarding
 182   // various status messages to the console, skips network error pages, and
 183   // short circuits size update and focus events.
 184   bool layout_test_mode() const {
 185     return layout_test_mode_;
 186   }
 187   void set_layout_test_mode(bool layout_test_mode) {
 188     layout_test_mode_ = layout_test_mode;
 189   }
 190
 191   IPC::ForwardingMessageFilter* compositor_output_surface_filter() const {
 192     return compositor_output_surface_filter_.get();
 193   }
 194
 195   InputHandlerManager* input_handler_manager() const {
 196     return input_handler_manager_.get();
 197   }
 198
 199   // Will be NULL if threaded compositing has not been enabled.
 200   scoped_refptr<base::MessageLoopProxy> compositor_message_loop_proxy() const {
 201     return compositor_message_loop_proxy_;
 202   }
 203
 204   bool is_gpu_rasterization_enabled() const {
 205     return is_gpu_rasterization_enabled_;
 206   }
 207
 208   bool is_gpu_rasterization_forced() const {
 209     return is_gpu_rasterization_forced_;
 210   }
 211
 212   bool is_impl_side_painting_enabled() const {
 213     return is_impl_side_painting_enabled_;
 214   }
 215
 216   bool is_low_res_tiling_enabled() const { return is_low_res_tiling_enabled_; }
 217
 218   bool is_lcd_text_enabled() const { return is_lcd_text_enabled_; }
 219
 220   bool is_distance_field_text_enabled() const {
 221     return is_distance_field_text_enabled_;
 222   }
 223
 224   bool is_zero_copy_enabled() const { return is_zero_copy_enabled_; }
 225
 226   bool is_one_copy_enabled() const { return is_one_copy_enabled_; }
 227
 228   AppCacheDispatcher* appcache_dispatcher() const {
 229     return appcache_dispatcher_.get();
 230   }
 231
 232   DomStorageDispatcher* dom_storage_dispatcher() const {
 233     return dom_storage_dispatcher_.get();
 234   }
 235
 236   EmbeddedWorkerDispatcher* embedded_worker_dispatcher() const {
 237     return embedded_worker_dispatcher_.get();
 238   }
 239
 240   AudioInputMessageFilter* audio_input_message_filter() {
 241     return audio_input_message_filter_.get();
 242   }
 243
 244   AudioMessageFilter* audio_message_filter() {
 245     return audio_message_filter_.get();
 246   }
 247
 248   MidiMessageFilter* midi_message_filter() {
 249     return midi_message_filter_.get();
 250   }
 251
 252 #if defined(OS_ANDROID)
 253   RendererDemuxerAndroid* renderer_demuxer() {
 254     return renderer_demuxer_.get();
 255   }
 256 #endif
 257
 258   // Creates the embedder implementation of WebMediaStreamCenter.
 259   // The resulting object is owned by WebKit and deleted by WebKit at tear-down.
 260   blink::WebMediaStreamCenter* CreateMediaStreamCenter(
 261       blink::WebMediaStreamCenterClient* client);
 262
 263   // Returns a factory used for creating RTC PeerConnection objects.
 264   PeerConnectionDependencyFactory* GetPeerConnectionDependencyFactory();
 265
 266   PeerConnectionTracker* peer_connection_tracker() {
 267     return peer_connection_tracker_.get();
 268   }
 269
 270   // Current P2PSocketDispatcher. Set to NULL if P2P API is disabled.
 271   P2PSocketDispatcher* p2p_socket_dispatcher() {
 272     return p2p_socket_dispatcher_.get();
 273   }
 274
 275   VideoCaptureImplManager* video_capture_impl_manager() const {
 276     return vc_manager_.get();
 277   }
 278
 279   GamepadSharedMemoryReader* gamepad_shared_memory_reader() const {
 280     return gamepad_shared_memory_reader_.get();
 281   }
 282
 283   // Get the GPU channel. Returns NULL if the channel is not established or
 284   // has been lost.
 285   GpuChannelHost* GetGpuChannel();
 286
 287   // Returns a MessageLoopProxy instance corresponding to the message loop
 288   // of the thread on which file operations should be run. Must be called
 289   // on the renderer's main thread.
 290   scoped_refptr<base::MessageLoopProxy> GetFileThreadMessageLoopProxy();
 291
 292   // Returns a MessageLoopProxy instance corresponding to the message loop
 293   // of the thread on which media operations should be run. Must be called
 294   // on the renderer's main thread.
 295   scoped_refptr<base::MessageLoopProxy> GetMediaThreadMessageLoopProxy();
 296
 297   // Causes the idle handler to skip sending idle notifications
 298   // on the two next scheduled calls, so idle notifications are
 299   // not sent for at least one notification delay.
 300   void PostponeIdleNotification();
 301
 302   scoped_refptr<media::GpuVideoAcceleratorFactories> GetGpuFactories();
 303
 304   scoped_refptr<webkit::gpu::ContextProviderWebContext>
 305       SharedMainThreadContextProvider();
 306
 307   // AudioRendererMixerManager instance which manages renderer side mixer
 308   // instances shared based on configured audio parameters.  Lazily created on
 309   // first call.
 310   AudioRendererMixerManager* GetAudioRendererMixerManager();
 311
 312   // AudioHardwareConfig contains audio hardware configuration for
 313   // renderer side clients.  Creation requires a synchronous IPC call so it is
 314   // lazily created on the first call.
 315   media::AudioHardwareConfig* GetAudioHardwareConfig();
 316
 317 #if defined(OS_WIN)
 318   void PreCacheFontCharacters(const LOGFONT& log_font,
 319                               const base::string16& str);
 320 #endif
 321
 322 #if defined(ENABLE_WEBRTC)
 323   WebRTCIdentityService* get_webrtc_identity_service() {
 324     return webrtc_identity_service_.get();
 325   }
 326 #endif
 327
 328   // For producing custom V8 histograms. Custom histograms are produced if all
 329   // RenderViews share the same host, and the host is in the pre-specified set
 330   // of hosts we want to produce custom diagrams for. The name for a custom
 331   // diagram is the name of the corresponding generic diagram plus a
 332   // host-specific suffix.
 333   class CONTENT_EXPORT HistogramCustomizer {
 334    public:
 335     HistogramCustomizer();
 336     ~HistogramCustomizer();
 337
 338     // Called when a top frame of a RenderView navigates. This function updates
 339     // RenderThreadImpl's information about whether all RenderViews are
 340     // displaying a page from the same host. |host| is the host where a
 341     // RenderView navigated, and |view_count| is the number of RenderViews in
 342     // this process.
 343     void RenderViewNavigatedToHost(const std::string& host, size_t view_count);
 344
 345     // Used for customizing some histograms if all RenderViews share the same
 346     // host. Returns the current custom histogram name to use for
 347     // |histogram_name|, or |histogram_name| if it shouldn't be customized.
 348     std::string ConvertToCustomHistogramName(const char* histogram_name) const;
 349
 350    private:
 351     friend class RenderThreadImplUnittest;
 352
 353     // Used for updating the information on which is the common host which all
 354     // RenderView's share (if any). If there is no common host, this function is
 355     // called with an empty string.
 356     void SetCommonHost(const std::string& host);
 357
 358     // The current common host of the RenderViews; empty string if there is no
 359     // common host.
 360     std::string common_host_;
 361     // The corresponding suffix.
 362     std::string common_host_histogram_suffix_;
 363     // Set of histograms for which we want to produce a custom histogram if
 364     // possible.
 365     std::set<std::string> custom_histograms_;
 366
 367     DISALLOW_COPY_AND_ASSIGN(HistogramCustomizer);
 368   };
 369
 370   HistogramCustomizer* histogram_customizer() {
 371     return &histogram_customizer_;
 372   }
 373
 374   void SetFlingCurveParameters(const std::vector<float>& new_touchpad,
 375                                const std::vector<float>& new_touchscreen);
 376
 377   // Retrieve current gamepad data.
 378   void SampleGamepads(blink::WebGamepads* data);
 379
 380   // Set a listener for gamepad connected/disconnected events.
 381   // A non-null listener must be set first before calling SampleGamepads.
 382   void SetGamepadListener(blink::WebGamepadListener* listener);
 383
 384   // Called by a RenderWidget when it is created or destroyed. This
 385   // allows the process to know when there are no visible widgets.
 386   void WidgetCreated();
 387   void WidgetDestroyed();
 388   void WidgetHidden();
 389   void WidgetRestored();
 390
 391   void AddEmbeddedWorkerRoute(int32 routing_id, IPC::Listener* listener);
 392   void RemoveEmbeddedWorkerRoute(int32 routing_id);
 393
 394  private:
 395   // ChildThread
 396   virtual bool OnControlMessageReceived(const IPC::Message& msg) OVERRIDE;
 397
 398   // GpuChannelHostFactory implementation:
 399   virtual bool IsMainThread() OVERRIDE;
 400   virtual base::MessageLoop* GetMainLoop() OVERRIDE;
 401   virtual scoped_refptr<base::MessageLoopProxy> GetIOLoopProxy() OVERRIDE;
 402   virtual scoped_ptr<base::SharedMemory> AllocateSharedMemory(
 403       size_t size) OVERRIDE;
 404   virtual bool CreateViewCommandBuffer(
 405       int32 surface_id,
 406       const GPUCreateCommandBufferConfig& init_params,
 407       int32 route_id) OVERRIDE;
 408   virtual void CreateImage(
 409       gfx::PluginWindowHandle window,
 410       int32 image_id,
 411       const CreateImageCallback& callback) OVERRIDE;
 412   virtual void DeleteImage(int32 image_id, int32 sync_point) OVERRIDE;
 413   virtual scoped_ptr<gfx::GpuMemoryBuffer> AllocateGpuMemoryBuffer(
 414       size_t width,
 415       size_t height,
 416       unsigned internalformat,
 417       unsigned usage) OVERRIDE;
 418
 419   // mojo::ServiceProvider implementation:
 420   virtual void ConnectToService(
 421       const mojo::String& service_name,
 422       mojo::ScopedMessagePipeHandle message_pipe) OVERRIDE;
 423
 424   void Init();
 425
 426   void OnSetZoomLevelForCurrentURL(const std::string& scheme,
 427                                    const std::string& host,
 428                                    double zoom_level);
 429   void OnCreateNewView(const ViewMsg_New_Params& params);
 430   void OnTransferBitmap(const SkBitmap& bitmap, int resource_id);
 431   void OnPurgePluginListCache(bool reload_pages);
 432   void OnNetworkStateChanged(bool online);
 433   void OnGetAccessibilityTree();
 434   void OnTempCrashWithData(const GURL& data);
 435   void OnUpdateTimezone();
 436   void OnMemoryPressure(
 437       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 438 #if defined(OS_ANDROID)
 439   void OnSetWebKitSharedTimersSuspended(bool suspend);
 440 #endif
 441 #if defined(OS_MACOSX)
 442   void OnUpdateScrollbarTheme(float initial_button_delay,
 443                               float autoscroll_button_delay,
 444                               bool jump_on_track_click,
 445                               blink::ScrollerStyle preferred_scroller_style,
 446                               bool redraw);
 447 #endif
 448   void OnCreateNewSharedWorker(
 449       const WorkerProcessMsg_CreateWorker_Params& params);
 450
 451   void IdleHandlerInForegroundTab();
 452
 453   scoped_ptr<WebGraphicsContext3DCommandBufferImpl> CreateOffscreenContext3d();
 454
 455   // These objects live solely on the render thread.
 456   scoped_ptr<AppCacheDispatcher> appcache_dispatcher_;
 457   scoped_ptr<DomStorageDispatcher> dom_storage_dispatcher_;
 458   scoped_ptr<IndexedDBDispatcher> main_thread_indexed_db_dispatcher_;
 459   scoped_ptr<RendererWebKitPlatformSupportImpl> webkit_platform_support_;
 460   scoped_ptr<EmbeddedWorkerDispatcher> embedded_worker_dispatcher_;
 461
 462   // Used on the render thread and deleted by WebKit at shutdown.
 463   blink::WebMediaStreamCenter* media_stream_center_;
 464
 465   // Used on the renderer and IPC threads.
 466   scoped_refptr<DBMessageFilter> db_message_filter_;
 467   scoped_refptr<AudioInputMessageFilter> audio_input_message_filter_;
 468   scoped_refptr<AudioMessageFilter> audio_message_filter_;
 469   scoped_refptr<MidiMessageFilter> midi_message_filter_;
 470 #if defined(OS_ANDROID)
 471   scoped_refptr<RendererDemuxerAndroid> renderer_demuxer_;
 472 #endif
 473   scoped_refptr<DevToolsAgentFilter> devtools_agent_message_filter_;
 474
 475   scoped_ptr<PeerConnectionDependencyFactory> peer_connection_factory_;
 476
 477   // This is used to communicate to the browser process the status
 478   // of all the peer connections created in the renderer.
 479   scoped_ptr<PeerConnectionTracker> peer_connection_tracker_;
 480
 481   // Dispatches all P2P sockets.
 482   scoped_refptr<P2PSocketDispatcher> p2p_socket_dispatcher_;
 483
 484   // Used on the render thread.
 485   scoped_ptr<VideoCaptureImplManager> vc_manager_;
 486
 487   // The count of RenderWidgets running through this thread.
 488   int widget_count_;
 489
 490   // The count of hidden RenderWidgets running through this thread.
 491   int hidden_widget_count_;
 492
 493   // The current value of the idle notification timer delay.
 494   int64 idle_notification_delay_in_ms_;
 495
 496   // The number of idle handler calls that skip sending idle notifications.
 497   int idle_notifications_to_skip_;
 498
 499   bool suspend_webkit_shared_timer_;
 500   bool notify_webkit_of_modal_loop_;
 501   bool webkit_shared_timer_suspended_;
 502
 503   // The following flag is used to control layout test specific behavior.
 504   bool layout_test_mode_;
 505
 506   // Timer that periodically calls IdleHandler.
 507   base::RepeatingTimer<RenderThreadImpl> idle_timer_;
 508
 509   // The channel from the renderer process to the GPU process.
 510   scoped_refptr<GpuChannelHost> gpu_channel_;
 511
 512   // Cache of variables that are needed on the compositor thread by
 513   // GpuChannelHostFactory methods.
 514   scoped_refptr<base::MessageLoopProxy> io_message_loop_proxy_;
 515
 516   // A lazily initiated thread on which file operations are run.
 517   scoped_ptr<base::Thread> file_thread_;
 518
 519   // May be null if overridden by ContentRendererClient.
 520   scoped_ptr<base::Thread> compositor_thread_;
 521
 522   // Thread for running multimedia operations (e.g., video decoding).
 523   scoped_ptr<base::Thread> media_thread_;
 524
 525   // Will point to appropriate MessageLoopProxy after initialization,
 526   // regardless of whether |compositor_thread_| is overriden.
 527   scoped_refptr<base::MessageLoopProxy> compositor_message_loop_proxy_;
 528
 529   // May be null if unused by the |input_handler_manager_|.
 530   scoped_refptr<InputEventFilter> input_event_filter_;
 531   scoped_ptr<InputHandlerManager> input_handler_manager_;
 532   scoped_refptr<IPC::ForwardingMessageFilter> compositor_output_surface_filter_;
 533
 534   scoped_refptr<ContextProviderCommandBuffer> shared_main_thread_contexts_;
 535
 536   ObserverList<RenderProcessObserver> observers_;
 537
 538   scoped_refptr<ContextProviderCommandBuffer> gpu_va_context_provider_;
 539
 540   scoped_ptr<AudioRendererMixerManager> audio_renderer_mixer_manager_;
 541   scoped_ptr<media::AudioHardwareConfig> audio_hardware_config_;
 542
 543   HistogramCustomizer histogram_customizer_;
 544
 545   scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 546
 547   scoped_ptr<WebRTCIdentityService> webrtc_identity_service_;
 548
 549   scoped_ptr<GamepadSharedMemoryReader> gamepad_shared_memory_reader_;
 550
 551   // TODO(reveman): Allow AllocateGpuMemoryBuffer to be called from
 552   // multiple threads. Current allocation mechanism for IOSurface
 553   // backed GpuMemoryBuffers prevent this. crbug.com/325045
 554   base::ThreadChecker allocate_gpu_memory_buffer_thread_checker_;
 555
 556   // Compositor settings
 557   bool is_gpu_rasterization_enabled_;
 558   bool is_gpu_rasterization_forced_;
 559   bool is_impl_side_painting_enabled_;
 560   bool is_low_res_tiling_enabled_;
 561   bool is_lcd_text_enabled_;
 562   bool is_distance_field_text_enabled_;
 563   bool is_zero_copy_enabled_;
 564   bool is_one_copy_enabled_;
 565
 566   DISALLOW_COPY_AND_ASSIGN(RenderThreadImpl);
 567 };
 568
 569 }  // namespace content
 570
 571 #endif  // CONTENT_RENDERER_RENDER_THREAD_IMPL_H_