BASELINE: Update Chromium to 55.0.2883.105

And updates ninja to 1.7.2

Change-Id: I20d43c737f82764d857ada9a55586901b18b9243
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

1 files changed, 154 insertions, 101 deletions

diff --git a/chromium/content/browser/browser_main_loop.cc b/chromium/content/browser/browser_main_loop.cc
index db8ea8df063..325b85d3ec2 100644
--- a/chromium/content/browser/browser_main_loop.cc
+++ b/chromium/content/browser/browser_main_loop.cc
@@ -19,7 +19,7 @@
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
 #include "base/pending_task.h"
 #include "base/power_monitor/power_monitor.h"
@@ -41,8 +41,9 @@
 #include "components/tracing/common/trace_to_console.h"
 #include "components/tracing/common/tracing_switches.h"
 #include "content/browser/browser_thread_impl.h"
-#include "content/browser/device_sensors/device_inertial_sensor_service.h"
+#include "content/browser/device_sensors/device_sensor_service.h"
 #include "content/browser/dom_storage/dom_storage_area.h"
+#include "content/browser/download/download_resource_handler.h"
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/gamepad/gamepad_service.h"
 #include "content/browser/gpu/browser_gpu_channel_host_factory.h"
@@ -55,22 +56,22 @@
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/loader_delegate_impl.h"
 #include "content/browser/media/media_internals.h"
-#include "content/browser/mojo/mojo_shell_context.h"
 #include "content/browser/net/browser_online_state_observer.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
+#include "content/browser/service_manager/service_manager_context.h"
 #include "content/browser/speech/speech_recognition_manager_impl.h"
 #include "content/browser/startup_task_runner.h"
-#include "content/browser/time_zone_monitor.h"
 #include "content/browser/utility_process_host_impl.h"
 #include "content/browser/webui/content_web_ui_controller_factory.h"
 #include "content/browser/webui/url_data_manager.h"
 #include "content/common/content_switches_internal.h"
 #include "content/common/host_discardable_shared_memory_manager.h"
 #include "content/common/host_shared_bitmap_manager.h"
-#include "content/common/mojo/mojo_shell_connection_impl.h"
+#include "content/common/service_manager/service_manager_connection_impl.h"
 #include "content/public/browser/browser_main_parts.h"
 #include "content/public/browser/content_browser_client.h"
+#include "content/public/browser/gpu_data_manager_observer.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/tracing_controller.h"
 #include "content/public/common/content_client.h"
@@ -78,6 +79,7 @@
 #include "content/public/common/main_function_params.h"
 #include "content/public/common/result_codes.h"
 #include "device/battery/battery_status_service.h"
+#include "device/time_zone_monitor/time_zone_monitor.h"
 #include "media/base/media.h"
 #include "media/base/user_input_monitor.h"
 #include "media/midi/midi_manager.h"
@@ -106,8 +108,10 @@
 #include "components/tracing/common/graphics_memory_dump_provider_android.h"
 #include "content/browser/android/browser_startup_controller.h"
 #include "content/browser/android/browser_surface_texture_manager.h"
+#include "content/browser/android/scoped_surface_request_manager.h"
 #include "content/browser/android/tracing_controller_android.h"
 #include "content/browser/media/android/browser_media_player_manager.h"
+#include "content/browser/renderer_host/context_provider_factory_impl_android.h"
 #include "content/browser/screen_orientation/screen_orientation_delegate_android.h"
 #include "content/public/browser/screen_orientation_provider.h"
 #include "gpu/ipc/client/android/in_process_surface_texture_manager.h"
@@ -152,11 +156,11 @@
 #endif
 
 #if defined(OS_WIN)
-#include "media/capture/system_message_window_win.h"
+#include "media/device_monitors/system_message_window_win.h"
 #elif defined(OS_LINUX) && defined(USE_UDEV)
-#include "media/capture/device_monitor_udev.h"
+#include "media/device_monitors/device_monitor_udev.h"
 #elif defined(OS_MACOSX)
-#include "media/capture/device_monitor_mac.h"
+#include "media/device_monitors/device_monitor_mac.h"
 #endif
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
@@ -178,9 +182,9 @@
 #endif
 
 #if defined(USE_X11)
+#include "gpu/config/gpu_driver_bug_workaround_type.h"
 #include "ui/base/x/x11_util_internal.h"  // nogncheck
 #include "ui/gfx/x/x11_connection.h"  // nogncheck
-#include "ui/gfx/x/x11_switches.h"  // nogncheck
 #include "ui/gfx/x/x11_types.h"  // nogncheck
 #endif
 
@@ -192,11 +196,6 @@
 #include "gpu/vulkan/vulkan_implementation.h"
 #endif
 
-#if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
-#include "components/mus/common/gpu_service.h"  // nogncheck
-#endif
-
-
 // One of the linux specific headers defines this as a macro.
 #ifdef DestroyAll
 #undef DestroyAll
@@ -208,6 +207,11 @@ namespace {
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
 void SetupSandbox(const base::CommandLine& parsed_command_line) {
   TRACE_EVENT0("startup", "SetupSandbox");
+  if (parsed_command_line.HasSwitch(switches::kNoZygote)) {
+    CHECK(parsed_command_line.HasSwitch(switches::kNoSandbox))
+        << "--no-sandbox should be used together with --no--zygote";
+    return;
+  }
 
   // Tickle the sandbox host and zygote host so they fork now.
   RenderSandboxHostLinux::GetInstance()->Init();
@@ -279,16 +283,6 @@ static void SetUpGLibLogHandler() {
 }
 #endif  // defined(USE_GLIB)
 
-#if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
-void WaitForMojoShellInitialize() {
-  // TODO(rockot): Remove this. http://crbug.com/594852.
-  base::RunLoop wait_loop;
-  MojoShellConnection::GetForProcess()->GetShellConnection()->
-      set_initialize_handler(wait_loop.QuitClosure());
-  wait_loop.Run();
-}
-#endif  // defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
-
 void OnStoppedStartupTracing(const base::FilePath& trace_file) {
   VLOG(0) << "Completed startup tracing to " << trace_file.value();
 }
@@ -376,6 +370,44 @@ base::win::MemoryPressureMonitor* CreateWinMemoryPressureMonitor(
 
 }  // namespace
 
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+namespace internal {
+
+// Forwards GPUInfo updates to ui::XVisualManager
+class GpuDataManagerVisualProxy : public GpuDataManagerObserver {
+ public:
+  explicit GpuDataManagerVisualProxy(GpuDataManagerImpl* gpu_data_manager)
+      : gpu_data_manager_(gpu_data_manager) {
+    gpu_data_manager_->AddObserver(this);
+  }
+
+  ~GpuDataManagerVisualProxy() override {
+    gpu_data_manager_->RemoveObserver(this);
+  }
+
+  void OnGpuInfoUpdate() override {
+    gpu::GPUInfo gpu_info = gpu_data_manager_->GetGPUInfo();
+    if (!ui::XVisualManager::GetInstance()->OnGPUInfoChanged(
+            gpu_info.software_rendering ||
+                !gpu_data_manager_->GpuAccessAllowed(nullptr),
+            gpu_info.system_visual, gpu_info.rgba_visual)) {
+      // The GPU process sent back bad visuals, which should never happen.
+      auto* gpu_process_host = GpuProcessHost::Get(
+          GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED, false);
+      if (gpu_process_host)
+        gpu_process_host->ForceShutdown();
+    }
+  }
+
+ private:
+  GpuDataManagerImpl* gpu_data_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuDataManagerVisualProxy);
+};
+
+}  // namespace internal
+#endif
+
 // The currently-running BrowserMainLoop.  There can be one or zero.
 BrowserMainLoop* g_current_browser_main_loop = NULL;
 
@@ -479,17 +511,16 @@ void BrowserMainLoop::EarlyInitialization() {
   if (parts_)
     parts_->PreEarlyInitialization();
 
-#if defined(OS_MACOSX)
-  // We use quite a few file descriptors for our IPC, and the default limit on
-  // the Mac is low (256), so bump it up.
-  base::SetFdLimit(1024);
-#elif defined(OS_LINUX)
+#if defined(OS_MACOSX) || defined(OS_LINUX)
+  // We use quite a few file descriptors for our IPC as well as disk the disk
+  // cache,and the default limit on the Mac is low (256), so bump it up.
+
   // Same for Linux. The default various per distro, but it is 1024 on Fedora.
   // Low soft limits combined with liberal use of file descriptors means power
   // users can easily hit this limit with many open tabs. Bump up the limit to
   // an arbitrarily high number. See https://crbug.com/539567
   base::SetFdLimit(8192);
-#endif  // default(OS_MACOSX)
+#endif  // defined(OS_MACOSX) || defined(OS_LINUX)
 
 #if defined(OS_WIN)
   net::EnsureWinsockInit();
@@ -587,7 +618,7 @@ void BrowserMainLoop::PostMainMessageLoopStart() {
 
   {
     base::SetRecordActionTaskRunner(
-        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI));
+        BrowserThread::GetTaskRunnerForThread(BrowserThread::UI));
   }
 
 #if defined(OS_WIN)
@@ -640,6 +671,8 @@ void BrowserMainLoop::PostMainMessageLoopStart() {
     if (parsed_command_line_.HasSwitch(switches::kSingleProcess)) {
       gpu::SurfaceTextureManager::SetInstance(
           gpu::InProcessSurfaceTextureManager::GetInstance());
+      gpu::ScopedSurfaceRequestConduit::SetInstance(
+          ScopedSurfaceRequestManager::GetInstance());
     } else {
       gpu::SurfaceTextureManager::SetInstance(
           BrowserSurfaceTextureManager::GetInstance());
@@ -755,7 +788,13 @@ int BrowserMainLoop::PreCreateThreads() {
   // It's unsafe to append the gpu command line switches to the global
   // CommandLine::ForCurrentProcess object after threads are created.
   // 2) Must be after parts_->PreCreateThreads to pick up chrome://flags.
-  GpuDataManagerImpl::GetInstance()->Initialize();
+  GpuDataManagerImpl* gpu_data_manager = GpuDataManagerImpl::GetInstance();
+  gpu_data_manager->Initialize();
+
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+  gpu_data_manager_visual_proxy_.reset(
+      new internal::GpuDataManagerVisualProxy(gpu_data_manager));
+#endif
 
 #if !defined(GOOGLE_CHROME_BUILD) || defined(OS_ANDROID)
   // Single-process is an unsupported and not fully tested mode, so
@@ -773,12 +812,12 @@ void BrowserMainLoop::CreateStartupTasks() {
   // First time through, we really want to create all the tasks
   if (!startup_task_runner_.get()) {
 #if defined(OS_ANDROID)
-    startup_task_runner_ = base::WrapUnique(
-        new StartupTaskRunner(base::Bind(&BrowserStartupComplete),
-                              base::ThreadTaskRunnerHandle::Get()));
+    startup_task_runner_ = base::MakeUnique<StartupTaskRunner>(
+        base::Bind(&BrowserStartupComplete),
+        base::ThreadTaskRunnerHandle::Get());
 #else
-    startup_task_runner_ = base::WrapUnique(new StartupTaskRunner(
-        base::Callback<void(int)>(), base::ThreadTaskRunnerHandle::Get()));
+    startup_task_runner_ = base::MakeUnique<StartupTaskRunner>(
+        base::Callback<void(int)>(), base::ThreadTaskRunnerHandle::Get());
 #endif
     StartupTask pre_create_threads =
         base::Bind(&BrowserMainLoop::PreCreateThreads, base::Unretained(this));
@@ -817,7 +856,7 @@ void BrowserMainLoop::CreateStartupTasks() {
 }
 
 int BrowserMainLoop::CreateThreads() {
-  TRACE_EVENT0("startup", "BrowserMainLoop::CreateThreads");
+  TRACE_EVENT0("startup,rail", "BrowserMainLoop::CreateThreads");
 
   base::Thread::Options io_message_loop_options;
   io_message_loop_options.message_loop_type = base::MessageLoop::TYPE_IO;
@@ -1027,7 +1066,7 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
 #endif
 
   // Shutdown Mojo shell and IPC.
-  mojo_shell_context_.reset();
+  service_manager_context_.reset();
   mojo_ipc_support_.reset();
 
   // Must be size_t so we can subtract from it.
@@ -1061,8 +1100,7 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
         TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:FileThread");
         // Clean up state that lives on or uses the file_thread_ before
         // it goes away.
-        if (resource_dispatcher_host_)
-          resource_dispatcher_host_.get()->save_file_manager()->Shutdown();
+        save_file_manager_->Shutdown();
         ResetThread_FILE(std::move(file_thread_));
         break;
       }
@@ -1113,8 +1151,14 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   // it.
   {
     TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUChannelFactory");
-    if (BrowserGpuChannelHostFactory::instance())
+    if (BrowserGpuChannelHostFactory::instance()) {
+#if defined(OS_ANDROID)
+      // Clean up the references to the factory before terminating it.
+      ui::ContextProviderFactory::SetInstance(nullptr);
+      ContextProviderFactoryImpl::Terminate();
+#endif
       BrowserGpuChannelHostFactory::Terminate();
+    }
   }
 
   // Must happen after the I/O thread is shutdown since this class lives on the
@@ -1125,7 +1169,7 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   }
   {
     TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:SensorService");
-    DeviceInertialSensorService::GetInstance()->Shutdown();
+    DeviceSensorService::GetInstance()->Shutdown();
   }
 #if !defined(OS_ANDROID)
   {
@@ -1160,34 +1204,17 @@ void BrowserMainLoop::InitializeMainThread() {
 int BrowserMainLoop::BrowserThreadsStarted() {
   TRACE_EVENT0("startup", "BrowserMainLoop::BrowserThreadsStarted");
 
-  // Bring up Mojo IPC and shell as early as possible.
-
-  // Disallow mojo sync call in the browser process.
-  bool sync_call_allowed = false;
-  MojoResult result = mojo::edk::SetProperty(
-      MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED, &sync_call_allowed);
-  DCHECK_EQ(MOJO_RESULT_OK, result);
+  // Bring up Mojo IPC and shell as early as possible. Initializaing mojo
+  // requires the IO thread to have been initialized first. So this cannot
+  // happen any earlier than this.
+  InitializeMojo();
 
-  mojo_ipc_support_.reset(new mojo::edk::ScopedIPCSupport(
-      BrowserThread::UnsafeGetMessageLoopForThread(BrowserThread::IO)
-          ->task_runner()));
-
-  mojo_shell_context_.reset(new MojoShellContext);
+#if defined(USE_AURA)
   if (shell::ShellIsRemote()) {
-#if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
-    // TODO(rockot): Remove the blocking wait for init.
-    // http://crbug.com/594852.
-    auto connection = MojoShellConnection::GetForProcess();
-    if (connection) {
-      WaitForMojoShellInitialize();
-      mus::GpuService::Initialize(connection->GetConnector());
-    }
-#endif
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        switches::kIsRunningInMash);
   }
-
-#if defined(OS_MACOSX)
-  mojo::edk::SetMachPortProvider(MachBroker::GetInstance());
-#endif  // defined(OS_MACOSX)
+#endif
 
   indexed_db_thread_.reset(new base::Thread("IndexedDB"));
   indexed_db_thread_->Start();
@@ -1212,20 +1239,29 @@ int BrowserMainLoop::BrowserThreadsStarted() {
   established_gpu_channel = false;
   always_uses_gpu = ShouldStartGpuProcessOnBrowserStartup();
   BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
+  ContextProviderFactoryImpl::Initialize(
+      BrowserGpuChannelHostFactory::instance());
+  ui::ContextProviderFactory::SetInstance(
+      ContextProviderFactoryImpl::GetInstance());
 #elif defined(USE_AURA) || defined(OS_MACOSX)
   established_gpu_channel = true;
   if (!GpuDataManagerImpl::GetInstance()->CanUseGpuBrowserCompositor() ||
-      parsed_command_line_.HasSwitch(switches::kDisableGpuEarlyInit)) {
+      parsed_command_line_.HasSwitch(switches::kDisableGpuEarlyInit) ||
+      shell::ShellIsRemote()) {
     established_gpu_channel = always_uses_gpu = false;
   }
-  BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
+  gpu::GpuChannelEstablishFactory* factory =
+      GetContentClient()->browser()->GetGpuChannelEstablishFactory();
+  if (!factory) {
+    BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
+    factory = BrowserGpuChannelHostFactory::instance();
+  }
+  DCHECK(factory);
   ImageTransportFactory::Initialize();
+  ImageTransportFactory::GetInstance()->SetGpuChannelEstablishFactory(factory);
 #if defined(USE_AURA)
-  bool use_mus_in_renderer = false;
-#if defined (MOJO_SHELL_CLIENT)
-  use_mus_in_renderer = base::CommandLine::ForCurrentProcess()->HasSwitch(
+  bool use_mus_in_renderer = base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kUseMusInRenderer);
-#endif  // defined(MOJO_SHELL_CLIENT);
   if (aura::Env::GetInstance() && !use_mus_in_renderer) {
     aura::Env::GetInstance()->set_context_factory(GetContextFactory());
   }
@@ -1272,7 +1308,14 @@ int BrowserMainLoop::BrowserThreadsStarted() {
   {
     TRACE_EVENT0("startup",
       "BrowserMainLoop::BrowserThreadsStarted:InitResourceDispatcherHost");
-    resource_dispatcher_host_.reset(new ResourceDispatcherHostImpl());
+    // TODO(ananta)
+    // We register an interceptor on the ResourceDispatcherHostImpl instance to
+    // intercept requests to create handlers for download requests. We need to
+    // find a better way to achieve this. Ideally we don't want knowledge of
+    // downloads in ResourceDispatcherHostImpl.
+    resource_dispatcher_host_.reset(new ResourceDispatcherHostImpl(
+        base::Bind(&DownloadResourceHandler::Create)));
+    GetContentClient()->browser()->ResourceDispatcherHostCreated();
 
     loader_delegate_.reset(new LoaderDelegateImpl());
     resource_dispatcher_host_->SetLoaderDelegate(loader_delegate_.get());
@@ -1303,7 +1346,14 @@ int BrowserMainLoop::BrowserThreadsStarted() {
   {
     TRACE_EVENT0("startup",
                  "BrowserMainLoop::BrowserThreadsStarted::TimeZoneMonitor");
-    time_zone_monitor_ = TimeZoneMonitor::Create();
+    time_zone_monitor_ =
+        device::TimeZoneMonitor::Create(file_thread_->task_runner());
+  }
+
+  {
+    TRACE_EVENT0("startup",
+      "BrowserMainLoop::BrowserThreadsStarted::SaveFileManager");
+    save_file_manager_ = new SaveFileManager();
   }
 
   // Alert the clipboard class to which threads are allowed to access the
@@ -1322,16 +1372,15 @@ int BrowserMainLoop::BrowserThreadsStarted() {
   // since creating the GPU thread races against creation of the one-and-only
   // ChildProcess instance which is created by the renderer thread.
   if (GpuDataManagerImpl::GetInstance()->GpuAccessAllowed(NULL) &&
-      !established_gpu_channel &&
-      always_uses_gpu &&
-      !UsingInProcessGpu()) {
+      !established_gpu_channel && always_uses_gpu && !UsingInProcessGpu() &&
+      !shell::ShellIsRemote()) {
     TRACE_EVENT_INSTANT0("gpu", "Post task to launch GPU process",
                          TRACE_EVENT_SCOPE_THREAD);
     BrowserThread::PostTask(
         BrowserThread::IO, FROM_HERE,
         base::Bind(base::IgnoreResult(&GpuProcessHost::Get),
                    GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED,
-                   CAUSE_FOR_GPU_LAUNCH_BROWSER_STARTUP));
+                   true /* force_create */));
   }
 
 #if defined(OS_MACOSX)
@@ -1377,20 +1426,6 @@ bool BrowserMainLoop::InitializeToolkit() {
     LOG(ERROR) << "Unable to open X display.";
     return false;
   }
-
-#if !defined(OS_CHROMEOS)
-  // InitializeToolkit is called before CreateStartupTasks which one starts the
-  // gpu process.
-  Visual* visual = NULL;
-  int depth = 0;
-  ui::ChooseVisualForWindow(&visual, &depth);
-  DCHECK(depth > 0);
-  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
-      switches::kWindowDepth, base::IntToString(depth));
-  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
-      switches::kX11VisualID, base::UintToString(visual->visualid));
-#endif
-
 #endif
 
   // Env creates the compositor. Aura widgets need the compositor to be created
@@ -1420,6 +1455,31 @@ void BrowserMainLoop::MainMessageLoopRun() {
 #endif
 }
 
+void BrowserMainLoop::InitializeMojo() {
+  if (!parsed_command_line_.HasSwitch(switches::kSingleProcess)) {
+    // Disallow mojo sync calls in the browser process. Note that we allow sync
+    // calls in single-process mode since renderer IPCs are made from a browser
+    // thread.
+    bool sync_call_allowed = false;
+    MojoResult result = mojo::edk::SetProperty(
+        MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED, &sync_call_allowed);
+    DCHECK_EQ(MOJO_RESULT_OK, result);
+  }
+
+  mojo_ipc_support_.reset(new mojo::edk::ScopedIPCSupport(
+      BrowserThread::UnsafeGetMessageLoopForThread(BrowserThread::IO)
+          ->task_runner()));
+
+  service_manager_context_.reset(new ServiceManagerContext);
+#if defined(OS_MACOSX)
+  mojo::edk::SetMachPortProvider(MachBroker::GetInstance());
+#endif  // defined(OS_MACOSX)
+  if (parts_) {
+    parts_->ServiceManagerConnectionStarted(
+        ServiceManagerConnection::GetForProcess());
+  }
+}
+
 base::FilePath BrowserMainLoop::GetStartupTraceFileName(
     const base::CommandLine& command_line) const {
   base::FilePath trace_file;
@@ -1490,7 +1550,6 @@ void BrowserMainLoop::CreateAudioManager() {
   DCHECK(!audio_thread_);
   DCHECK(!audio_manager_);
 
-  bool use_hang_monitor = true;
   audio_manager_ = GetContentClient()->browser()->CreateAudioManager(
       MediaInternals::GetInstance());
   if (!audio_manager_) {
@@ -1502,9 +1561,6 @@ void BrowserMainLoop::CreateAudioManager() {
 #if defined(OS_MACOSX)
     // On Mac audio task runner must belong to the main thread.
     // See http://crbug.com/158170.
-    // Since the audio thread is the UI thread, a hang monitor is not
-    // necessary or recommended.
-    use_hang_monitor = false;
     scoped_refptr<base::SingleThreadTaskRunner> audio_task_runner =
         base::ThreadTaskRunnerHandle::Get();
 #else
@@ -1518,9 +1574,6 @@ void BrowserMainLoop::CreateAudioManager() {
                                                  MediaInternals::GetInstance());
   }
   CHECK(audio_manager_);
-
-  if (use_hang_monitor)
-    media::AudioManager::StartHangMonitor(io_thread_->task_runner());
 }
 
 }  // namespace content