Handle audio device changes on Mac (Take 2).

media/audio/mac/audio_manager_mac.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_MAC_AUDIO_MANAGER_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "media/audio/audio_manager_base.h"
 
 namespace media {
 
 // Mac OS X implementation of the AudioManager singleton. This class is internal
 // to the audio output and only internal users can call methods not exposed by
 // the AudioManager class.
 class MEDIA_EXPORT AudioManagerMac : public AudioManagerBase {
  public:
@@ skipping 12 matching lines @@
       const AudioParameters& params) OVERRIDE;
   virtual AudioInputStream* MakeLinearInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
   virtual AudioInputStream* MakeLowLatencyInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
 
  protected:
   virtual ~AudioManagerMac();
 
  private:
+  // Listens for output device changes.
+  base::Closure listener_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_