content/child/child_thread_impl.cc

   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 #include "content/child/child_thread_impl.h"
   6
   7 #include <signal.h>
   8
   9 #include <string>
  10
  11 #include "base/allocator/allocator_extension.h"
  12 #include "base/base_switches.h"
  13 #include "base/basictypes.h"
  14 #include "base/command_line.h"
  15 #include "base/debug/leak_annotations.h"
  16 #include "base/debug/profiler.h"
  17 #include "base/lazy_instance.h"
  18 #include "base/location.h"
  19 #include "base/logging.h"
  20 #include "base/message_loop/timer_slack.h"
  21 #include "base/metrics/field_trial.h"
  22 #include "base/process/process.h"
  23 #include "base/process/process_handle.h"
  24 #include "base/single_thread_task_runner.h"
  25 #include "base/strings/string_number_conversions.h"
  26 #include "base/strings/string_util.h"
  27 #include "base/synchronization/condition_variable.h"
  28 #include "base/synchronization/lock.h"
  29 #include "base/thread_task_runner_handle.h"
  30 #include "base/threading/thread_local.h"
  31 #include "base/trace_event/memory_dump_manager.h"
  32 #include "base/tracked_objects.h"
  33 #include "components/tracing/child_trace_message_filter.h"
  34 #include "content/child/child_discardable_shared_memory_manager.h"
  35 #include "content/child/child_gpu_memory_buffer_manager.h"
  36 #include "content/child/child_histogram_message_filter.h"
  37 #include "content/child/child_process.h"
  38 #include "content/child/child_resource_message_filter.h"
  39 #include "content/child/child_shared_bitmap_manager.h"
  40 #include "content/child/fileapi/file_system_dispatcher.h"
  41 #include "content/child/fileapi/webfilesystem_impl.h"
  42 #include "content/child/geofencing/geofencing_message_filter.h"
  43 #include "content/child/mojo/mojo_application.h"
  44 #include "content/child/notifications/notification_dispatcher.h"
  45 #include "content/child/power_monitor_broadcast_source.h"
  46 #include "content/child/push_messaging/push_dispatcher.h"
  47 #include "content/child/quota_dispatcher.h"
  48 #include "content/child/quota_message_filter.h"
  49 #include "content/child/resource_dispatcher.h"
  50 #include "content/child/service_worker/service_worker_message_filter.h"
  51 #include "content/child/thread_safe_sender.h"
  52 #include "content/child/websocket_dispatcher.h"
  53 #include "content/common/child_process_messages.h"
  54 #include "content/common/in_process_child_thread_params.h"
  55 #include "content/public/common/content_switches.h"
  56 #include "ipc/attachment_broker_unprivileged.h"
  57 #include "ipc/ipc_logging.h"
  58 #include "ipc/ipc_switches.h"
  59 #include "ipc/ipc_sync_channel.h"
  60 #include "ipc/ipc_sync_message_filter.h"
  61 #include "ipc/mojo/ipc_channel_mojo.h"
  62
  63 #if defined(TCMALLOC_TRACE_MEMORY_SUPPORTED)
  64 #include "third_party/tcmalloc/chromium/src/gperftools/heap-profiler.h"
  65 #endif
  66
  67 #if defined(OS_MACOSX)
  68 #include "content/child/child_io_surface_manager_mac.h"
  69 #endif
  70
  71 #if defined(OS_WIN)
  72 #include "ipc/attachment_broker_unprivileged_win.h"
  73 #endif
  74
  75 using tracked_objects::ThreadData;
  76
  77 namespace content {
  78 namespace {
  79
  80 // How long to wait for a connection to the browser process before giving up.
  81 const int kConnectionTimeoutS = 15;
  82
  83 base::LazyInstance<base::ThreadLocalPointer<ChildThreadImpl> > g_lazy_tls =
  84     LAZY_INSTANCE_INITIALIZER;
  85
  86 // This isn't needed on Windows because there the sandbox's job object
  87 // terminates child processes automatically. For unsandboxed processes (i.e.
  88 // plugins), PluginThread has EnsureTerminateMessageFilter.
  89 #if defined(OS_POSIX)
  90
  91 #if defined(ADDRESS_SANITIZER) || defined(LEAK_SANITIZER) || \
  92     defined(MEMORY_SANITIZER) || defined(THREAD_SANITIZER) || \
  93     defined(UNDEFINED_SANITIZER)
  94 // A thread delegate that waits for |duration| and then exits the process with
  95 // _exit(0).
  96 class WaitAndExitDelegate : public base::PlatformThread::Delegate {
  97  public:
  98   explicit WaitAndExitDelegate(base::TimeDelta duration)
  99       : duration_(duration) {}
 100
 101   void ThreadMain() override {
 102     base::PlatformThread::Sleep(duration_);
 103     _exit(0);
 104   }
 105
 106  private:
 107   const base::TimeDelta duration_;
 108   DISALLOW_COPY_AND_ASSIGN(WaitAndExitDelegate);
 109 };
 110
 111 bool CreateWaitAndExitThread(base::TimeDelta duration) {
 112   scoped_ptr<WaitAndExitDelegate> delegate(new WaitAndExitDelegate(duration));
 113
 114   const bool thread_created =
 115       base::PlatformThread::CreateNonJoinable(0, delegate.get());
 116   if (!thread_created)
 117     return false;
 118
 119   // A non joinable thread has been created. The thread will either terminate
 120   // the process or will be terminated by the process. Therefore, keep the
 121   // delegate object alive for the lifetime of the process.
 122   WaitAndExitDelegate* leaking_delegate = delegate.release();
 123   ANNOTATE_LEAKING_OBJECT_PTR(leaking_delegate);
 124   ignore_result(leaking_delegate);
 125   return true;
 126 }
 127 #endif
 128
 129 class SuicideOnChannelErrorFilter : public IPC::MessageFilter {
 130  public:
 131   // IPC::MessageFilter
 132   void OnChannelError() override {
 133     // For renderer/worker processes:
 134     // On POSIX, at least, one can install an unload handler which loops
 135     // forever and leave behind a renderer process which eats 100% CPU forever.
 136     //
 137     // This is because the terminate signals (FrameMsg_BeforeUnload and the
 138     // error from the IPC sender) are routed to the main message loop but never
 139     // processed (because that message loop is stuck in V8).
 140     //
 141     // One could make the browser SIGKILL the renderers, but that leaves open a
 142     // large window where a browser failure (or a user, manually terminating
 143     // the browser because "it's stuck") will leave behind a process eating all
 144     // the CPU.
 145     //
 146     // So, we install a filter on the sender so that we can process this event
 147     // here and kill the process.
 148     base::debug::StopProfiling();
 149 #if defined(ADDRESS_SANITIZER) || defined(LEAK_SANITIZER) || \
 150     defined(MEMORY_SANITIZER) || defined(THREAD_SANITIZER) || \
 151     defined(UNDEFINED_SANITIZER)
 152     // Some sanitizer tools rely on exit handlers (e.g. to run leak detection,
 153     // or dump code coverage data to disk). Instead of exiting the process
 154     // immediately, we give it 60 seconds to run exit handlers.
 155     CHECK(CreateWaitAndExitThread(base::TimeDelta::FromSeconds(60)));
 156 #if defined(LEAK_SANITIZER)
 157     // Invoke LeakSanitizer early to avoid detecting shutdown-only leaks. If
 158     // leaks are found, the process will exit here.
 159     __lsan_do_leak_check();
 160 #endif
 161 #else
 162     _exit(0);
 163 #endif
 164   }
 165
 166  protected:
 167   ~SuicideOnChannelErrorFilter() override {}
 168 };
 169
 170 #endif  // OS(POSIX)
 171
 172 #if defined(OS_MACOSX)
 173 class IOSurfaceManagerFilter : public IPC::MessageFilter {
 174  public:
 175   // Overridden from IPC::MessageFilter:
 176   bool OnMessageReceived(const IPC::Message& message) override {
 177     bool handled = true;
 178     IPC_BEGIN_MESSAGE_MAP(IOSurfaceManagerFilter, message)
 179       IPC_MESSAGE_HANDLER(ChildProcessMsg_SetIOSurfaceManagerToken,
 180                           OnSetIOSurfaceManagerToken)
 181       IPC_MESSAGE_UNHANDLED(handled = false)
 182     IPC_END_MESSAGE_MAP()
 183     return handled;
 184   }
 185
 186  protected:
 187   ~IOSurfaceManagerFilter() override {}
 188
 189   void OnSetIOSurfaceManagerToken(const IOSurfaceManagerToken& token) {
 190     ChildIOSurfaceManager::GetInstance()->set_token(token);
 191   }
 192 };
 193 #endif
 194
 195 #if defined(OS_ANDROID)
 196 // A class that allows for triggering a clean shutdown from another
 197 // thread through draining the main thread's msg loop.
 198 class QuitClosure {
 199  public:
 200   QuitClosure();
 201   ~QuitClosure();
 202
 203   void BindToMainThread();
 204   void PostQuitFromNonMainThread();
 205
 206  private:
 207   static void PostClosure(
 208       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
 209       base::Closure closure);
 210
 211   base::Lock lock_;
 212   base::ConditionVariable cond_var_;
 213   base::Closure closure_;
 214 };
 215
 216 QuitClosure::QuitClosure() : cond_var_(&lock_) {
 217 }
 218
 219 QuitClosure::~QuitClosure() {
 220 }
 221
 222 void QuitClosure::PostClosure(
 223     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
 224     base::Closure closure) {
 225   task_runner->PostTask(FROM_HERE, closure);
 226 }
 227
 228 void QuitClosure::BindToMainThread() {
 229   base::AutoLock lock(lock_);
 230   scoped_refptr<base::SingleThreadTaskRunner> task_runner(
 231       base::ThreadTaskRunnerHandle::Get());
 232   base::Closure quit_closure =
 233       base::MessageLoop::current()->QuitWhenIdleClosure();
 234   closure_ = base::Bind(&QuitClosure::PostClosure, task_runner, quit_closure);
 235   cond_var_.Signal();
 236 }
 237
 238 void QuitClosure::PostQuitFromNonMainThread() {
 239   base::AutoLock lock(lock_);
 240   while (closure_.is_null())
 241     cond_var_.Wait();
 242
 243   closure_.Run();
 244 }
 245
 246 base::LazyInstance<QuitClosure> g_quit_closure = LAZY_INSTANCE_INITIALIZER;
 247 #endif
 248
 249 }  // namespace
 250
 251 ChildThread* ChildThread::Get() {
 252   return ChildThreadImpl::current();
 253 }
 254
 255 ChildThreadImpl::Options::Options()
 256     : channel_name(base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
 257           switches::kProcessChannelID)),
 258       use_mojo_channel(false) {
 259 }
 260
 261 ChildThreadImpl::Options::~Options() {
 262 }
 263
 264 ChildThreadImpl::Options::Builder::Builder() {
 265 }
 266
 267 ChildThreadImpl::Options::Builder&
 268 ChildThreadImpl::Options::Builder::InBrowserProcess(
 269     const InProcessChildThreadParams& params) {
 270   options_.browser_process_io_runner = params.io_runner();
 271   options_.channel_name = params.channel_name();
 272   return *this;
 273 }
 274
 275 ChildThreadImpl::Options::Builder&
 276 ChildThreadImpl::Options::Builder::UseMojoChannel(bool use_mojo_channel) {
 277   options_.use_mojo_channel = use_mojo_channel;
 278   return *this;
 279 }
 280
 281 ChildThreadImpl::Options::Builder&
 282 ChildThreadImpl::Options::Builder::WithChannelName(
 283     const std::string& channel_name) {
 284   options_.channel_name = channel_name;
 285   return *this;
 286 }
 287
 288 ChildThreadImpl::Options::Builder&
 289 ChildThreadImpl::Options::Builder::AddStartupFilter(
 290     IPC::MessageFilter* filter) {
 291   options_.startup_filters.push_back(filter);
 292   return *this;
 293 }
 294
 295 ChildThreadImpl::Options ChildThreadImpl::Options::Builder::Build() {
 296   return options_;
 297 }
 298
 299 ChildThreadImpl::ChildThreadMessageRouter::ChildThreadMessageRouter(
 300     IPC::Sender* sender)
 301     : sender_(sender) {}
 302
 303 bool ChildThreadImpl::ChildThreadMessageRouter::Send(IPC::Message* msg) {
 304   return sender_->Send(msg);
 305 }
 306
 307 ChildThreadImpl::ChildThreadImpl()
 308     : router_(this),
 309       channel_connected_factory_(this) {
 310   Init(Options::Builder().Build());
 311 }
 312
 313 ChildThreadImpl::ChildThreadImpl(const Options& options)
 314     : router_(this),
 315       browser_process_io_runner_(options.browser_process_io_runner),
 316       channel_connected_factory_(this) {
 317   Init(options);
 318 }
 319
 320 scoped_refptr<base::SequencedTaskRunner> ChildThreadImpl::GetIOTaskRunner() {
 321   if (IsInBrowserProcess())
 322     return browser_process_io_runner_;
 323   return ChildProcess::current()->io_task_runner();
 324 }
 325
 326 void ChildThreadImpl::ConnectChannel(bool use_mojo_channel) {
 327   bool create_pipe_now = true;
 328   if (use_mojo_channel) {
 329     VLOG(1) << "Mojo is enabled on child";
 330     scoped_refptr<base::SequencedTaskRunner> io_task_runner = GetIOTaskRunner();
 331     DCHECK(io_task_runner);
 332     channel_->Init(IPC::ChannelMojo::CreateClientFactory(
 333                        io_task_runner, channel_name_, attachment_broker_.get()),
 334                    create_pipe_now);
 335     return;
 336   }
 337
 338   VLOG(1) << "Mojo is disabled on child";
 339   channel_->Init(channel_name_, IPC::Channel::MODE_CLIENT, create_pipe_now,
 340                  attachment_broker_.get());
 341 }
 342
 343 void ChildThreadImpl::Init(const Options& options) {
 344   channel_name_ = options.channel_name;
 345
 346   g_lazy_tls.Pointer()->Set(this);
 347   on_channel_error_called_ = false;
 348   message_loop_ = base::MessageLoop::current();
 349 #ifdef IPC_MESSAGE_LOG_ENABLED
 350   // We must make sure to instantiate the IPC Logger *before* we create the
 351   // channel, otherwise we can get a callback on the IO thread which creates
 352   // the logger, and the logger does not like being created on the IO thread.
 353   IPC::Logging::GetInstance();
 354 #endif
 355   channel_ =
 356       IPC::SyncChannel::Create(this, ChildProcess::current()->io_task_runner(),
 357                                ChildProcess::current()->GetShutDownEvent());
 358 #ifdef IPC_MESSAGE_LOG_ENABLED
 359   if (!IsInBrowserProcess())
 360     IPC::Logging::GetInstance()->SetIPCSender(this);
 361 #endif
 362
 363 #if defined(OS_WIN)
 364   attachment_broker_.reset(new IPC::AttachmentBrokerUnprivilegedWin());
 365 #endif
 366
 367   mojo_application_.reset(new MojoApplication(GetIOTaskRunner()));
 368
 369   sync_message_filter_ = channel_->CreateSyncMessageFilter();
 370   thread_safe_sender_ = new ThreadSafeSender(
 371       message_loop_->task_runner(), sync_message_filter_.get());
 372
 373   resource_dispatcher_.reset(new ResourceDispatcher(
 374       this, message_loop()->task_runner()));
 375   websocket_dispatcher_.reset(new WebSocketDispatcher);
 376   file_system_dispatcher_.reset(new FileSystemDispatcher());
 377
 378   histogram_message_filter_ = new ChildHistogramMessageFilter();
 379   resource_message_filter_ =
 380       new ChildResourceMessageFilter(resource_dispatcher());
 381
 382   service_worker_message_filter_ =
 383       new ServiceWorkerMessageFilter(thread_safe_sender_.get());
 384
 385   quota_message_filter_ =
 386       new QuotaMessageFilter(thread_safe_sender_.get());
 387   quota_dispatcher_.reset(new QuotaDispatcher(thread_safe_sender_.get(),
 388                                               quota_message_filter_.get()));
 389   geofencing_message_filter_ =
 390       new GeofencingMessageFilter(thread_safe_sender_.get());
 391   notification_dispatcher_ =
 392       new NotificationDispatcher(thread_safe_sender_.get());
 393   push_dispatcher_ = new PushDispatcher(thread_safe_sender_.get());
 394
 395   channel_->AddFilter(histogram_message_filter_.get());
 396   channel_->AddFilter(resource_message_filter_.get());
 397   channel_->AddFilter(quota_message_filter_->GetFilter());
 398   channel_->AddFilter(notification_dispatcher_->GetFilter());
 399   channel_->AddFilter(push_dispatcher_->GetFilter());
 400   channel_->AddFilter(service_worker_message_filter_->GetFilter());
 401   channel_->AddFilter(geofencing_message_filter_->GetFilter());
 402
 403   if (!IsInBrowserProcess()) {
 404     // In single process mode, browser-side tracing will cover the whole
 405     // process including renderers.
 406     channel_->AddFilter(new tracing::ChildTraceMessageFilter(
 407         ChildProcess::current()->io_task_runner()));
 408   }
 409
 410   // In single process mode we may already have a power monitor
 411   if (!base::PowerMonitor::Get()) {
 412     scoped_ptr<PowerMonitorBroadcastSource> power_monitor_source(
 413       new PowerMonitorBroadcastSource());
 414     channel_->AddFilter(power_monitor_source->GetMessageFilter());
 415
 416     power_monitor_.reset(new base::PowerMonitor(
 417         power_monitor_source.Pass()));
 418   }
 419
 420 #if defined(OS_POSIX)
 421   // Check that --process-type is specified so we don't do this in unit tests
 422   // and single-process mode.
 423   if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kProcessType))
 424     channel_->AddFilter(new SuicideOnChannelErrorFilter());
 425 #endif
 426
 427 #if defined(OS_MACOSX)
 428   channel_->AddFilter(new IOSurfaceManagerFilter());
 429 #endif
 430
 431   // Add filters passed here via options.
 432   for (auto startup_filter : options.startup_filters) {
 433     channel_->AddFilter(startup_filter);
 434   }
 435
 436   ConnectChannel(options.use_mojo_channel);
 437   if (attachment_broker_)
 438     attachment_broker_->DesignateBrokerCommunicationChannel(channel_.get());
 439
 440   int connection_timeout = kConnectionTimeoutS;
 441   std::string connection_override =
 442       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
 443           switches::kIPCConnectionTimeout);
 444   if (!connection_override.empty()) {
 445     int temp;
 446     if (base::StringToInt(connection_override, &temp))
 447       connection_timeout = temp;
 448   }
 449
 450   message_loop_->task_runner()->PostDelayedTask(
 451       FROM_HERE, base::Bind(&ChildThreadImpl::EnsureConnected,
 452                             channel_connected_factory_.GetWeakPtr()),
 453       base::TimeDelta::FromSeconds(connection_timeout));
 454
 455 #if defined(OS_ANDROID)
 456   g_quit_closure.Get().BindToMainThread();
 457 #endif
 458
 459 #if defined(TCMALLOC_TRACE_MEMORY_SUPPORTED)
 460   trace_memory_controller_.reset(new base::trace_event::TraceMemoryController(
 461       message_loop_->task_runner(), ::HeapProfilerWithPseudoStackStart,
 462       ::HeapProfilerStop, ::GetHeapProfile));
 463 #endif
 464
 465   base::trace_event::MemoryDumpManager::GetInstance()->Initialize();
 466
 467   shared_bitmap_manager_.reset(
 468       new ChildSharedBitmapManager(thread_safe_sender()));
 469
 470   gpu_memory_buffer_manager_.reset(
 471       new ChildGpuMemoryBufferManager(thread_safe_sender()));
 472
 473   discardable_shared_memory_manager_.reset(
 474       new ChildDiscardableSharedMemoryManager(thread_safe_sender()));
 475 }
 476
 477 ChildThreadImpl::~ChildThreadImpl() {
 478   // ChildDiscardableSharedMemoryManager has to be destroyed while
 479   // |thread_safe_sender_| is still valid.
 480   discardable_shared_memory_manager_.reset();
 481
 482 #ifdef IPC_MESSAGE_LOG_ENABLED
 483   IPC::Logging::GetInstance()->SetIPCSender(NULL);
 484 #endif
 485
 486   channel_->RemoveFilter(histogram_message_filter_.get());
 487   channel_->RemoveFilter(sync_message_filter_.get());
 488
 489   // The ChannelProxy object caches a pointer to the IPC thread, so need to
 490   // reset it as it's not guaranteed to outlive this object.
 491   // NOTE: this also has the side-effect of not closing the main IPC channel to
 492   // the browser process.  This is needed because this is the signal that the
 493   // browser uses to know that this process has died, so we need it to be alive
 494   // until this process is shut down, and the OS closes the handle
 495   // automatically.  We used to watch the object handle on Windows to do this,
 496   // but it wasn't possible to do so on POSIX.
 497   channel_->ClearIPCTaskRunner();
 498   g_lazy_tls.Pointer()->Set(NULL);
 499 }
 500
 501 void ChildThreadImpl::Shutdown() {
 502   // Delete objects that hold references to blink so derived classes can
 503   // safely shutdown blink in their Shutdown implementation.
 504   file_system_dispatcher_.reset();
 505   quota_dispatcher_.reset();
 506   WebFileSystemImpl::DeleteThreadSpecificInstance();
 507 }
 508
 509 void ChildThreadImpl::OnChannelConnected(int32 peer_pid) {
 510   channel_connected_factory_.InvalidateWeakPtrs();
 511 }
 512
 513 void ChildThreadImpl::OnChannelError() {
 514   set_on_channel_error_called(true);
 515   base::MessageLoop::current()->Quit();
 516 }
 517
 518 bool ChildThreadImpl::Send(IPC::Message* msg) {
 519   DCHECK(base::MessageLoop::current() == message_loop());
 520   if (!channel_) {
 521     delete msg;
 522     return false;
 523   }
 524
 525   return channel_->Send(msg);
 526 }
 527
 528 #if defined(OS_WIN)
 529 void ChildThreadImpl::PreCacheFont(const LOGFONT& log_font) {
 530   Send(new ChildProcessHostMsg_PreCacheFont(log_font));
 531 }
 532
 533 void ChildThreadImpl::ReleaseCachedFonts() {
 534   Send(new ChildProcessHostMsg_ReleaseCachedFonts());
 535 }
 536 #endif
 537
 538 IPC::AttachmentBroker* ChildThreadImpl::GetAttachmentBroker() {
 539   return attachment_broker_.get();
 540 }
 541
 542 MessageRouter* ChildThreadImpl::GetRouter() {
 543   DCHECK(base::MessageLoop::current() == message_loop());
 544   return &router_;
 545 }
 546
 547 scoped_ptr<base::SharedMemory> ChildThreadImpl::AllocateSharedMemory(
 548     size_t buf_size) {
 549   DCHECK(base::MessageLoop::current() == message_loop());
 550   return AllocateSharedMemory(buf_size, this);
 551 }
 552
 553 // static
 554 scoped_ptr<base::SharedMemory> ChildThreadImpl::AllocateSharedMemory(
 555     size_t buf_size,
 556     IPC::Sender* sender) {
 557   scoped_ptr<base::SharedMemory> shared_buf;
 558 #if defined(OS_WIN)
 559   shared_buf.reset(new base::SharedMemory);
 560   if (!shared_buf->CreateAnonymous(buf_size)) {
 561     NOTREACHED();
 562     return NULL;
 563   }
 564 #else
 565   // On POSIX, we need to ask the browser to create the shared memory for us,
 566   // since this is blocked by the sandbox.
 567   base::SharedMemoryHandle shared_mem_handle;
 568   if (sender->Send(new ChildProcessHostMsg_SyncAllocateSharedMemory(
 569                            buf_size, &shared_mem_handle))) {
 570     if (base::SharedMemory::IsHandleValid(shared_mem_handle)) {
 571       shared_buf.reset(new base::SharedMemory(shared_mem_handle, false));
 572     } else {
 573       NOTREACHED() << "Browser failed to allocate shared memory";
 574       return NULL;
 575     }
 576   } else {
 577     NOTREACHED() << "Browser allocation request message failed";
 578     return NULL;
 579   }
 580 #endif
 581   return shared_buf;
 582 }
 583
 584 bool ChildThreadImpl::OnMessageReceived(const IPC::Message& msg) {
 585   if (mojo_application_->OnMessageReceived(msg))
 586     return true;
 587
 588   // Resource responses are sent to the resource dispatcher.
 589   if (resource_dispatcher_->OnMessageReceived(msg))
 590     return true;
 591   if (websocket_dispatcher_->OnMessageReceived(msg))
 592     return true;
 593   if (file_system_dispatcher_->OnMessageReceived(msg))
 594     return true;
 595
 596   bool handled = true;
 597   IPC_BEGIN_MESSAGE_MAP(ChildThreadImpl, msg)
 598     IPC_MESSAGE_HANDLER(ChildProcessMsg_Shutdown, OnShutdown)
 599 #if defined(IPC_MESSAGE_LOG_ENABLED)
 600     IPC_MESSAGE_HANDLER(ChildProcessMsg_SetIPCLoggingEnabled,
 601                         OnSetIPCLoggingEnabled)
 602 #endif
 603     IPC_MESSAGE_HANDLER(ChildProcessMsg_SetProfilerStatus,
 604                         OnSetProfilerStatus)
 605     IPC_MESSAGE_HANDLER(ChildProcessMsg_GetChildProfilerData,
 606                         OnGetChildProfilerData)
 607     IPC_MESSAGE_HANDLER(ChildProcessMsg_ProfilingPhaseCompleted,
 608                         OnProfilingPhaseCompleted)
 609     IPC_MESSAGE_HANDLER(ChildProcessMsg_SetProcessBackgrounded,
 610                         OnProcessBackgrounded)
 611 #if defined(USE_TCMALLOC)
 612     IPC_MESSAGE_HANDLER(ChildProcessMsg_GetTcmallocStats, OnGetTcmallocStats)
 613 #endif
 614     IPC_MESSAGE_UNHANDLED(handled = false)
 615   IPC_END_MESSAGE_MAP()
 616
 617   if (handled)
 618     return true;
 619
 620   if (msg.routing_id() == MSG_ROUTING_CONTROL)
 621     return OnControlMessageReceived(msg);
 622
 623   return router_.OnMessageReceived(msg);
 624 }
 625
 626 bool ChildThreadImpl::OnControlMessageReceived(const IPC::Message& msg) {
 627   return false;
 628 }
 629
 630 void ChildThreadImpl::OnShutdown() {
 631   base::MessageLoop::current()->Quit();
 632 }
 633
 634 #if defined(IPC_MESSAGE_LOG_ENABLED)
 635 void ChildThreadImpl::OnSetIPCLoggingEnabled(bool enable) {
 636   if (enable)
 637     IPC::Logging::GetInstance()->Enable();
 638   else
 639     IPC::Logging::GetInstance()->Disable();
 640 }
 641 #endif  //  IPC_MESSAGE_LOG_ENABLED
 642
 643 void ChildThreadImpl::OnSetProfilerStatus(ThreadData::Status status) {
 644   ThreadData::InitializeAndSetTrackingStatus(status);
 645 }
 646
 647 void ChildThreadImpl::OnGetChildProfilerData(int sequence_number,
 648                                              int current_profiling_phase) {
 649   tracked_objects::ProcessDataSnapshot process_data;
 650   ThreadData::Snapshot(current_profiling_phase, &process_data);
 651
 652   Send(
 653       new ChildProcessHostMsg_ChildProfilerData(sequence_number, process_data));
 654 }
 655
 656 void ChildThreadImpl::OnProfilingPhaseCompleted(int profiling_phase) {
 657   ThreadData::OnProfilingPhaseCompleted(profiling_phase);
 658 }
 659
 660 #if defined(USE_TCMALLOC)
 661 void ChildThreadImpl::OnGetTcmallocStats() {
 662   std::string result;
 663   char buffer[1024 * 32];
 664   base::allocator::GetStats(buffer, sizeof(buffer));
 665   result.append(buffer);
 666   Send(new ChildProcessHostMsg_TcmallocStats(result));
 667 }
 668 #endif
 669
 670 ChildThreadImpl* ChildThreadImpl::current() {
 671   return g_lazy_tls.Pointer()->Get();
 672 }
 673
 674 #if defined(OS_ANDROID)
 675 // The method must NOT be called on the child thread itself.
 676 // It may block the child thread if so.
 677 void ChildThreadImpl::ShutdownThread() {
 678   DCHECK(!ChildThreadImpl::current()) <<
 679       "this method should NOT be called from child thread itself";
 680   g_quit_closure.Get().PostQuitFromNonMainThread();
 681 }
 682 #endif
 683
 684 void ChildThreadImpl::OnProcessFinalRelease() {
 685   if (on_channel_error_called_) {
 686     base::MessageLoop::current()->Quit();
 687     return;
 688   }
 689
 690   // The child process shutdown sequence is a request response based mechanism,
 691   // where we send out an initial feeler request to the child process host
 692   // instance in the browser to verify if it's ok to shutdown the child process.
 693   // The browser then sends back a response if it's ok to shutdown. This avoids
 694   // race conditions if the process refcount is 0 but there's an IPC message
 695   // inflight that would addref it.
 696   Send(new ChildProcessHostMsg_ShutdownRequest);
 697 }
 698
 699 void ChildThreadImpl::EnsureConnected() {
 700   VLOG(0) << "ChildThreadImpl::EnsureConnected()";
 701   base::Process::Current().Terminate(0, false);
 702 }
 703
 704 bool ChildThreadImpl::IsInBrowserProcess() const {
 705   return browser_process_io_runner_;
 706 }
 707
 708 void ChildThreadImpl::OnProcessBackgrounded(bool background) {
 709   // Set timer slack to maximum on main thread when in background.
 710   base::TimerSlack timer_slack = base::TIMER_SLACK_NONE;
 711   if (background)
 712     timer_slack = base::TIMER_SLACK_MAXIMUM;
 713   base::MessageLoop::current()->SetTimerSlack(timer_slack);
 714 }
 715
 716 }  // namespace content