Use audio thread for the fake input audio stream.

media/audio/fake_audio_input_stream.h

Index: media/audio/fake_audio_input_stream.h
diff --git a/media/audio/fake_audio_input_stream.h b/media/audio/fake_audio_input_stream.h
index e6c625e6b3a2dd843630728667a1e2efd7e5f8ec..4c3c24c55552ed93a5c6c1860bf9b473059503cc 100644
--- a/media/audio/fake_audio_input_stream.h
+++ b/media/audio/fake_audio_input_stream.h
@@ -61,7 +61,7 @@ class MEDIA_EXPORT FakeAudioInputStream
   scoped_ptr<uint8[]> buffer_;
   int buffer_size_;
   AudioParameters params_;
-  base::Thread thread_;
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   base::TimeTicks last_callback_time_;
   base::TimeDelta callback_interval_;
   base::TimeDelta interval_from_last_beep_;
@@ -71,6 +71,10 @@ class MEDIA_EXPORT FakeAudioInputStream
   int frames_elapsed_;
   scoped_ptr<media::AudioBus> audio_bus_;
 
+  // Allows us to run tasks on the FakeAudioInputStream instance which are
+  // bound by its lifetime.
+  base::WeakPtrFactory<FakeAudioInputStream> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(FakeAudioInputStream);
 };