Remove MediaStreamDeviceThread in favor of using AudioThread.

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 14095ac32a1c587bd71c688f10674450a5cccb19..09541aff70a8ca4f7949363d7c6ebdbddef5cde6 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -11,7 +11,6 @@
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/rand_util.h"
-#include "base/threading/thread.h"
 #include "content/browser/renderer_host/media/audio_input_device_manager.h"
 #include "content/browser/renderer_host/media/media_stream_requester.h"
 #include "content/browser/renderer_host/media/media_stream_ui_proxy.h"
@@ -149,7 +148,7 @@ MediaStreamManager::MediaStreamManager(media::AudioManager* audio_manager)
 
 MediaStreamManager::~MediaStreamManager() {
   DCHECK(requests_.empty());
-  DCHECK(!device_thread_.get());
+  DCHECK(!device_loop_);
   DCHECK(!io_loop_);
 }
 
@@ -582,22 +581,15 @@ void MediaStreamManager::HandleRequest(const std::string& label) {
 
 void MediaStreamManager::InitializeDeviceManagersOnIOThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (device_thread_)
+  if (device_loop_)
     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_loop_ = audio_manager_->GetMessageLoop();
 
   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_loop_);
 
   video_capture_manager_ = new VideoCaptureManager();
-  video_capture_manager_->Register(this,
-                                   device_thread_->message_loop_proxy().get());
+  video_capture_manager_->Register(this, device_loop_);
 
   // We want to be notified of IO message loop destruction to delete the thread
   // and the device managers.
@@ -942,12 +934,12 @@ void MediaStreamManager::UseFakeUI(scoped_ptr<FakeMediaStreamUIProxy> fake_ui) {
 void MediaStreamManager::WillDestroyCurrentMessageLoop() {
   DCHECK_EQ(base::MessageLoop::current(), io_loop_);
   DCHECK(requests_.empty());
-  if (device_thread_) {
+  if (device_loop_) {
     StopMonitoring();
 
     video_capture_manager_->Unregister();
     audio_input_device_manager_->Unregister();
-    device_thread_.reset();
+    device_loop_ = NULL;

[no longer working on chromium, 2013/06/21 20:44:25]

will this work?
Previously we join the device_thread when the IO thread is dying, then the
device managers won't post tasks to IO thread anymore, WIth this change, the
audio_thread will outlive the IO thread, so it might post tasks to IO thread
after IO thread dies, what will happen then?

[DaleCurtis, 2013/06/21 20:48:15]

Ah... yeah there's a problem here.  I'll see if I can figure out a clean way
around it.

[DaleCurtis, 2013/06/21 22:15:07]

Actually this isn't a problem.  I thought it was because the unittests were
falling over, but they were falling over because we weren't actually using a
BrowserThread (which can handle post-death tasks cleanly).  I've fixed this by
switching them over to ajwong's sweet TestBrowserThreadBundle.

At this point the IO thread is dead, so any new tasks posted to it are dropped.
The BrowserThread::PostTask code takes care of this.  Since both
AudioInputDeviceManager and VideoCaptureManager are refcounted, they won't be
destructed until any outstanding AudioManager loop tasks are completed.

   }
 
   audio_input_device_manager_ = NULL;