Use the browser UI thread for audio on OSX.

media/audio/audio_input_controller.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_INPUT_CONTROLLER_H_
 #define MEDIA_AUDIO_AUDIO_INPUT_CONTROLLER_H_
 
 #include <string>
 #include "base/atomicops.h"
 #include "base/callback.h"
@@ skipping 133 matching lines @@
       const AudioParameters& params,
       const std::string& device_id,
       // External synchronous writer for audio controller.
       SyncWriter* sync_writer);
 
   // Factory method for creating an AudioInputController for low-latency mode,
   // taking ownership of |stream|.  The stream will be opened on the audio
   // thread, and when that is done, the event handler will receive an
   // OnCreated() call from that same thread.
   static scoped_refptr<AudioInputController> CreateForStream(
-      AudioManager* audio_manager,
+      const scoped_refptr<base::MessageLoopProxy>& message_loop,
       EventHandler* event_handler,
       AudioInputStream* stream,
       // External synchronous writer for audio controller.
       SyncWriter* sync_writer);
 
   // Starts recording using the created audio input stream.
   // This method is called on the creator thread.
   virtual void Record();
 
   // Closes the audio input stream. The state is changed and the resources
@@ skipping 99 matching lines @@
   static Factory* factory_;
 
   double max_volume_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_INPUT_CONTROLLER_H_