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

media/audio/audio_manager.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 29 matching lines @@
   // which must not be NULL.
   static void SetFactory(AudioManagerFactory* factory);
 
   // Construct the audio manager; only one instance is allowed.  The manager
   // will forward CreateAudioLog() calls to the provided AudioLogFactory; as
   // such |audio_log_factory| must outlive the AudioManager.
   static AudioManager* Create(AudioLogFactory* audio_log_factory);
 
   // 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);
 
   // 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();
+
   // Should only be used for testing. Resets a previously-set
   // AudioManagerFactory. The instance of AudioManager is not affected.
   static void ResetFactoryForTesting();
 
   // 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.
   static AudioManager* Get();
 
   // Returns true if the OS reports existence of audio devices. This does not
@@ skipping 140 matching lines @@
  protected:
   AudioManager();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_H_