Handle audio device changes on Windows.

media/audio/win/audio_manager_win.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_WIN_AUDIO_MANAGER_WIN_H_
 #define MEDIA_AUDIO_WIN_AUDIO_MANAGER_WIN_H_
 
 #include <windows.h>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "media/audio/audio_manager_base.h"
+#include "media/audio/win/audio_device_listener_win.h"
 
 namespace media {
 
 // Windows 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 AudioManagerWin : public AudioManagerBase {
+class MEDIA_EXPORT AudioManagerWin
+    : public AudioManagerBase,
+      NON_EXPORTED_BASE(public AudioManager::AudioDeviceListener) {
  public:
   AudioManagerWin();
   // Implementation of AudioManager.
+  virtual void Init() OVERRIDE;
   virtual bool HasAudioOutputDevices() OVERRIDE;
   virtual bool HasAudioInputDevices() OVERRIDE;
   virtual string16 GetAudioInputDeviceModel() OVERRIDE;
   virtual bool CanShowAudioInputSettings() OVERRIDE;
   virtual void ShowAudioInputSettings() OVERRIDE;
   virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names)
       OVERRIDE;
 
   // Implementation of AudioManagerBase.
   virtual AudioOutputStream* MakeLinearOutputStream(
       const AudioParameters& params) OVERRIDE;
   virtual AudioOutputStream* MakeLowLatencyOutputStream(
       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;
   virtual AudioParameters GetPreferredLowLatencyOutputStreamParameters(
       const AudioParameters& input_params) OVERRIDE;
 
+  // AudioDeviceListener implementation.
+  virtual void OnDeviceChange() OVERRIDE;
+
  protected:
   virtual ~AudioManagerWin();
 
  private:
   enum EnumerationType {
     kUninitializedEnumeration = 0,
     kMMDeviceEnumeration,
     kWaveEnumeration,
   };
 
   // Allow unit test to modify the utilized enumeration API.
   friend class AudioInputDeviceTest;
 
   EnumerationType enumeration_type_;
   EnumerationType enumeration_type() { return enumeration_type_; }
   void SetEnumerationType(EnumerationType type) {
     enumeration_type_ = type;
   }
 
   // Returns a PCMWaveInAudioInputStream instance or NULL on failure.
   // This method converts MMDevice-style device ID to WaveIn-style device ID if
   // necessary.
   // (Please see device_enumeration_win.h for more info about the two kinds of
   // device IDs.)
   AudioInputStream* CreatePCMWaveInAudioInputStream(
       const AudioParameters& params,
       const std::string& device_id);
 
+  // Listen for output device changes.
+  scoped_ptr<AudioDeviceListenerWin> output_device_listener_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerWin);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_WIN_AUDIO_MANAGER_WIN_H_