AudioManagerBase: Create and run the audio thread lazily.

media/audio/mock_audio_manager.cc

Index: media/audio/mock_audio_manager.cc
diff --git a/media/audio/mock_audio_manager.cc b/media/audio/mock_audio_manager.cc
index e8aacbe875b0797994a26febc11426f5ae16cfd6..7183405a19063f1e44800336e1867ba7d4a9c733 100644
--- a/media/audio/mock_audio_manager.cc
+++ b/media/audio/mock_audio_manager.cc
@@ -63,8 +63,7 @@ media::AudioInputStream* MockAudioManager::MakeAudioInputStream(
   return NULL;
 }
 
-scoped_refptr<base::SingleThreadTaskRunner> MockAudioManager::GetTaskRunner()
-    const {
+scoped_refptr<base::SingleThreadTaskRunner> MockAudioManager::GetTaskRunner() {
   return task_runner_;
 }