[chromecast] Simplify CastAudioOutputStream.

chromecast/media/audio/cast_audio_output_stream.h

Index: chromecast/media/audio/cast_audio_output_stream.h
diff --git a/chromecast/media/audio/cast_audio_output_stream.h b/chromecast/media/audio/cast_audio_output_stream.h
index df775607037f02e7412ef531da23a986562a2290..fd2c6042afe739602d272d4f16624510385bb405 100644
--- a/chromecast/media/audio/cast_audio_output_stream.h
+++ b/chromecast/media/audio/cast_audio_output_stream.h
@@ -11,10 +11,6 @@
 #include "media/audio/audio_io.h"
 #include "media/base/audio_parameters.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}  // namespace base
-
 namespace chromecast {
 namespace media {
 
@@ -38,7 +34,6 @@ class CastAudioOutputStream : public ::media::AudioOutputStream {
  private:
   class Backend;
 
-  void OnClosed();
   void PushBuffer();
   void OnPushBufferComplete(bool success);
 
@@ -54,9 +49,6 @@ class CastAudioOutputStream : public ::media::AudioOutputStream {
   bool push_in_progress_;
   base::TimeTicks next_push_time_;
 
-  scoped_refptr<base::SingleThreadTaskRunner> audio_task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> backend_task_runner_;
-
   base::WeakPtrFactory<CastAudioOutputStream> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CastAudioOutputStream);