Rmoving the notion of task runner from MediaStreamProvider interface.

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 86ce133bd3a006ac231a1124d3dd16d6cf289576..1665fe38db98e14ddab21b1cbccaf3bfac91a20d 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -1227,7 +1227,7 @@ void MediaStreamManager::InitializeDeviceManagersOnIOThread() {
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "457525 MediaStreamManager::InitializeDeviceManagersOnIOThread 2"));
   audio_input_device_manager_ = new AudioInputDeviceManager(audio_manager_);
-  audio_input_device_manager_->Register(this, device_task_runner_);
+  audio_input_device_manager_->RegisterListener(this);
 
   // TODO(dalecurtis): Remove ScopedTracker below once crbug.com/457525 is
   // fixed.
@@ -1243,19 +1243,24 @@ void MediaStreamManager::InitializeDeviceManagersOnIOThread() {
   tracked_objects::ScopedTracker tracking_profile4(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "457525 MediaStreamManager::InitializeDeviceManagersOnIOThread 4"));
-  video_capture_manager_ =
-      new VideoCaptureManager(media::VideoCaptureDeviceFactory::CreateFactory(
-          BrowserThread::GetTaskRunnerForThread(BrowserThread::UI)));
 #if defined(OS_WIN)
   // Use an STA Video Capture Thread to try to avoid crashes on enumeration of
   // buggy third party Direct Show modules, http://crbug.com/428958.
   video_capture_thread_.init_com_with_mta(false);
   CHECK(video_capture_thread_.Start());
-  video_capture_manager_->Register(this, video_capture_thread_.task_runner());
+  video_capture_manager_ = new VideoCaptureManager(
+      media::VideoCaptureDeviceFactory::CreateFactory(
+          BrowserThread::GetTaskRunnerForThread(BrowserThread::UI)),
+      video_capture_thread_.task_runner());
 #else
-  video_capture_manager_->Register(this, device_task_runner_);
+  video_capture_manager_ = new VideoCaptureManager(
+      media::VideoCaptureDeviceFactory::CreateFactory(
+          BrowserThread::GetTaskRunnerForThread(BrowserThread::UI)),
+      device_task_runner_);
 #endif
 
+  video_capture_manager_->RegisterListener(this);
+
   media_devices_manager_.reset(
       new MediaDevicesManager(audio_manager_, video_capture_manager_, this));
 }
@@ -1543,18 +1548,18 @@ void MediaStreamManager::WillDestroyCurrentMessageLoop() {
   DVLOG(3) << "MediaStreamManager::WillDestroyCurrentMessageLoop()";
   DCHECK(CalledOnIOThread());
   DCHECK(requests_.empty());
-  if (device_task_runner_.get()) {
+  if (media_devices_manager_)
     media_devices_manager_->StopMonitoring();
+  if (video_capture_manager_)
+    video_capture_manager_->UnregisterListener();
+  if (audio_input_device_manager_)
+    audio_input_device_manager_->UnregisterListener();
 
-    video_capture_manager_->Unregister();
-    audio_input_device_manager_->Unregister();
-    device_task_runner_ = NULL;
-  }
-
-  audio_input_device_manager_ = NULL;
-  video_capture_manager_ = NULL;
-  media_devices_manager_ = NULL;
-  g_media_stream_manager_tls_ptr.Pointer()->Set(NULL);
+  device_task_runner_ = nullptr;
+  audio_input_device_manager_ = nullptr;
+  video_capture_manager_ = nullptr;
+  media_devices_manager_ = nullptr;
+  g_media_stream_manager_tls_ptr.Pointer()->Set(nullptr);
 }
 
 void MediaStreamManager::NotifyDevicesChanged(
@@ -1613,7 +1618,7 @@ MediaStreamProvider* MediaStreamManager::GetDeviceManager(
   else if (IsAudioInputMediaType(stream_type))
     return audio_input_device_manager();
   NOTREACHED();
-  return NULL;
+  return nullptr;
 }
 
 void MediaStreamManager::OnMediaStreamUIWindowId(MediaStreamType video_type,