Use the browser UI thread for audio on OSX.

media/audio/audio_manager_base.h

 // 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 21 matching lines @@
 class MEDIA_EXPORT AudioManagerBase : public AudioManager {
  public:
   // Name of the generic "default" device.
   static const char kDefaultDeviceName[];
   // Unique Id of the generic "default" device.
   static const char kDefaultDeviceId[];
 
   virtual ~AudioManagerBase();
 
   virtual scoped_refptr<base::MessageLoopProxy> GetMessageLoop() OVERRIDE;
+  virtual scoped_refptr<base::MessageLoopProxy> GetWorkerLoop() OVERRIDE;
 
   virtual string16 GetAudioInputDeviceModel() OVERRIDE;
 
   virtual void ShowAudioInputSettings() OVERRIDE;
 
   virtual void GetAudioInputDeviceNames(
       media::AudioDeviceNames* device_names) OVERRIDE;
 
   virtual AudioOutputStream* MakeAudioOutputStream(
       const AudioParameters& params) OVERRIDE;
@@ skipping 105 matching lines @@
   ObserverList<AudioDeviceListener> output_listeners_;
 
   // Thread used to interact with audio streams created by this audio manager.
   scoped_ptr<base::Thread> audio_thread_;
   mutable base::Lock audio_thread_lock_;
 
   // The message loop of the audio thread this object runs on. Used for internal
   // tasks which run on the audio thread even after Shutdown() has been started
   // and GetMessageLoop() starts returning NULL.
   scoped_refptr<base::MessageLoopProxy> message_loop_;
+  scoped_refptr<base::MessageLoopProxy> worker_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_