Use the browser UI thread for audio on OSX.

media/audio/mac/audio_device_listener_mac.h

Index: media/audio/mac/audio_device_listener_mac.h
diff --git a/media/audio/mac/audio_device_listener_mac.h b/media/audio/mac/audio_device_listener_mac.h
index d2d58706972687aa252a14110c9f73c100b92580..bc1a39c62d5b7bd2e71d7d045681a7d8b9519289 100644
--- a/media/audio/mac/audio_device_listener_mac.h
+++ b/media/audio/mac/audio_device_listener_mac.h
@@ -9,21 +9,13 @@
 
 #include "base/basictypes.h"
 #include "base/callback.h"
-#include "base/scoped_native_library.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
-class ExclusiveDispatchQueueTaskObserver;
-
-// AudioDeviceListenerMac facilitates thread safe execution of device listener
-// callbacks issued via CoreAudio.  On 10.6 this means correctly binding the
-// CFRunLoop driving callbacks to the CFRunLoop AudioDeviceListenerMac is
-// constructed on.  On 10.7 this means creating a dispatch queue to drive
-// callbacks and modifying the message loop AudioDeviceListenerMac to ensure
-// message loop tasks and dispatch queue tasks are executed in a mutually
-// exclusive manner.  See http://crbug.com/158170 for more discussion.
+// AudioDeviceListenerMac facilitates execution of device listener callbacks
+// issued via CoreAudio.
 class MEDIA_EXPORT AudioDeviceListenerMac {
  public:
   // |listener_cb| will be called when a device change occurs; it's a permanent
@@ -39,30 +31,7 @@ class MEDIA_EXPORT AudioDeviceListenerMac {
       AudioObjectID object, UInt32 num_addresses,
       const AudioObjectPropertyAddress addresses[], void* context);
 
-  // Attempts to dynamically load the property listener block functions.  Sets
-  // |core_audio_lib_|, |add_listener_block_func_|, and
-  // |remove_listener_block_func_|.  Returns false on failure.  If successful,
-  // the unload function must be called to avoid memory leaks.
-  bool LoadAudioObjectPropertyListenerBlockFunctions();
-
   base::Closure listener_cb_;
-  scoped_ptr<ExclusiveDispatchQueueTaskObserver> task_observer_;
-  base::ScopedNativeLibrary core_audio_lib_;
-
-  // TODO(dalecurtis): Use the standard AudioObjectPropertyListenerBlock when
-  // the deployment target is > 10.6.
-  typedef void (^CrAudioObjectPropertyListenerBlock)(
-      UInt32 inNumberAddresses, const AudioObjectPropertyAddress inAddresses[]);
-  CrAudioObjectPropertyListenerBlock listener_block_;
-
-  // Variables for storing dynamically loaded block functions.
-  typedef OSStatus(*AudioObjectPropertyListenerBlockT)(
-      AudioObjectID inObjectID,
-      const AudioObjectPropertyAddress* inAddress,
-      dispatch_queue_t inDispatchQueue,
-      CrAudioObjectPropertyListenerBlock inListener);
-  AudioObjectPropertyListenerBlockT add_listener_block_func_;
-  AudioObjectPropertyListenerBlockT remove_listener_block_func_;
 
   // AudioDeviceListenerMac must be constructed and destructed on the same
   // thread.