Remove MediaStreamDeviceThread in favor of audio worker TaskRunner.

content/browser/renderer_host/media/media_stream_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 
 #include <list>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 328 matching lines @@
     BrowserThread::PostTask(
         BrowserThread::IO, FROM_HERE,
         base::Bind(&MediaStreamManager::InitializeDeviceManagersOnIOThread,
                    base::Unretained(this)));
   }
 }
 
 MediaStreamManager::~MediaStreamManager() {
   DVLOG(1) << "~MediaStreamManager";
   DCHECK(requests_.empty());
-  DCHECK(!device_thread_.get());
+  DCHECK(!device_task_runner_);
 }
 
 VideoCaptureManager* MediaStreamManager::video_capture_manager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(video_capture_manager_.get());
   return video_capture_manager_.get();
 }
 
 AudioInputDeviceManager* MediaStreamManager::audio_input_device_manager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
@@ skipping 986 matching lines @@
     const MediaStreamDevices& devices) {
   if (!request->callback.is_null())
     request->callback.Run(devices, request->ui_proxy.Pass());
 
   // Delete the request since it is done.
   DeleteRequest(label);
 }
 
 void MediaStreamManager::InitializeDeviceManagersOnIOThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (device_thread_)
+  if (device_task_runner_)
     return;
 
-  device_thread_.reset(new base::Thread("MediaStreamDeviceThread"));
-#if defined(OS_WIN)
-  device_thread_->init_com_with_mta(true);
-#endif
-  CHECK(device_thread_->Start());
+  device_task_runner_ = audio_manager_->GetWorkerTaskRunner();

[henrika (OOO until Aug 14), 2014/02/05 08:42:03]

It is actually not clear to me when to use GetWorkerTaskRunner() and when to use
GetTaskRunner(). Any clear "rules"?

[DaleCurtis, 2014/02/05 21:47:11]

See the documentation for AudioManager::GetWorkerTaskRunner().  Heavyweight
(long) or high frequency tasks are good candidates.  However, it only really
matters on OSX since we have to use the UI thread as the audio thread there.

[henrika (OOO until Aug 14), 2014/02/05 21:52:22]

Thanks. The OS X part was not clear to me before.

 
   audio_input_device_manager_ = new AudioInputDeviceManager(audio_manager_);
-  audio_input_device_manager_->Register(
-      this, device_thread_->message_loop_proxy().get());
+  audio_input_device_manager_->Register(this, device_task_runner_);
 
   video_capture_manager_ = new VideoCaptureManager();
-  video_capture_manager_->Register(this,
-                                   device_thread_->message_loop_proxy().get());
+  video_capture_manager_->Register(this, device_task_runner_);
 
   // We want to be notified of IO message loop destruction to delete the thread
   // and the device managers.
   io_loop_ = base::MessageLoop::current();
   io_loop_->AddDestructionObserver(this);
 
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kUseFakeDeviceForMediaStream)) {
     DVLOG(1) << "Using fake device";
     UseFakeDevice();
@@ skipping 346 matching lines @@
 void MediaStreamManager::UseFakeUI(scoped_ptr<FakeMediaStreamUIProxy> fake_ui) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   use_fake_ui_ = true;
   fake_ui_ = fake_ui.Pass();
 }
 
 void MediaStreamManager::WillDestroyCurrentMessageLoop() {
   DVLOG(3) << "MediaStreamManager::WillDestroyCurrentMessageLoop()";
   DCHECK_EQ(base::MessageLoop::current(), io_loop_);
   DCHECK(requests_.empty());
-  if (device_thread_) {
+  if (device_task_runner_) {
     StopMonitoring();
 
     video_capture_manager_->Unregister();
     audio_input_device_manager_->Unregister();
-    device_thread_.reset();
+    device_task_runner_ = NULL;
   }
 
   audio_input_device_manager_ = NULL;
   video_capture_manager_ = NULL;
 }
 
 void MediaStreamManager::NotifyDevicesChanged(
     MediaStreamType stream_type,
     const StreamDeviceInfoArray& devices) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
@@ skipping 69 matching lines @@
   }
 
   // Always do enumeration even though some enumeration is in progress,
   // because those enumeration commands could be sent before these devices
   // change.
   ++active_enumeration_ref_count_[stream_type];
   GetDeviceManager(stream_type)->EnumerateDevices(stream_type);
 }
 
 }  // namespace content