Replace MessageLoopProxy with SingleThreadTaskRunner for the rest of media/.

media/audio/audio_output_dispatcher.h

Index: media/audio/audio_output_dispatcher.h
diff --git a/media/audio/audio_output_dispatcher.h b/media/audio/audio_output_dispatcher.h
index 52de79410f57c0dac716129f2a9da516a834d15c..e684d2890001672951b2f52a8a942a10fb86a33f 100644
--- a/media/audio/audio_output_dispatcher.h
+++ b/media/audio/audio_output_dispatcher.h
@@ -26,7 +26,7 @@
 #include "media/audio/audio_parameters.h"
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
 }
 
 namespace media {
@@ -78,7 +78,7 @@ class MEDIA_EXPORT AudioOutputDispatcher
   // A no-reference-held pointer (we don't want circular references) back to the
   // AudioManager that owns this object.
   AudioManager* audio_manager_;
-  const scoped_refptr<base::MessageLoopProxy> message_loop_;
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   const AudioParameters params_;
   const std::string output_device_id_;
   const std::string input_device_id_;