Switch audio hang monitor to default-off. Enable for non-beta,stable.

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index 5e49b8b399afd138c35f659d73823be06a0e9567..0b98d8673042430e24712348940a398fac6da8f0 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -36,7 +36,7 @@ class MEDIA_EXPORT AudioManager {
 
   // Similar to Create() except also schedules a monitor on the given task
   // runner to ensure the audio thread is not stuck for more than 60 seconds; if
-  // a hang is detected, the process will be crashed.
+  // a hang is detected, the process will be crashed.  See EnableHangMonitor().
   static AudioManager* CreateWithHangTimer(
       AudioLogFactory* audio_log_factory,
       const scoped_refptr<base::SingleThreadTaskRunner>& monitor_task_runner);
@@ -44,6 +44,12 @@ class MEDIA_EXPORT AudioManager {
   // Similar to Create() except uses a FakeAudioLogFactory for testing.
   static AudioManager* CreateForTesting();
 
+  // Enables the hang monitor for the AudioManager once it's created.  Must be
+  // called before the AudioManager is created.  CreateWithHangTimer() requires
+  // either switches::kEnableAudioHangMonitor to be present or this to have been
+  // called previously to start the hang monitor.  Does nothing on OSX.
+  static void EnableHangMonitor();
+
   // Returns the pointer to the last created instance, or NULL if not yet
   // created. This is a utility method for the code outside of media directory,
   // like src/chrome.