Handle audio device changes on Windows.

media/audio/win/audio_manager_win.h

Index: media/audio/win/audio_manager_win.h
diff --git a/media/audio/win/audio_manager_win.h b/media/audio/win/audio_manager_win.h
index 6a4efcbafbd91b11c3773b3fe3786570904e3f81..ab1aa5851f442a95c92700a0ddf0368116d049db 100644
--- a/media/audio/win/audio_manager_win.h
+++ b/media/audio/win/audio_manager_win.h
@@ -12,15 +12,19 @@
 #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) {

[scherkus (not reviewing), 2012/10/24 04:27:09]

I still don't see a reason to use multiple inheritance here.

Why not pass a AudioManagerWin* pointer into ADLWin?

[DaleCurtis, 2012/10/24 04:52:47]

Hmm, I kept it this way because the unit test was clear and simple.  One
alternative would be to create a real AudioManager() instance and register our
mock OnDeviceChange listener through the public AudioManager methods.  The test
would then need to friend AudioManagerWin so it can fake callbacks.  WDYT?

[scherkus (not reviewing), 2012/10/24 16:52:11]

Those darn unit tests!

OK what about using a callback instead of multiple inheritance? That's still a
win IMO.

[DaleCurtis, 2012/10/24 19:27:29]

Done.

  public:
   AudioManagerWin();
+
   // Implementation of AudioManager.
   virtual bool HasAudioOutputDevices() OVERRIDE;
   virtual bool HasAudioInputDevices() OVERRIDE;
@@ -42,9 +46,15 @@ class MEDIA_EXPORT AudioManagerWin : public AudioManagerBase {
   virtual AudioParameters GetPreferredLowLatencyOutputStreamParameters(
       const AudioParameters& input_params) OVERRIDE;
 
+  // AudioDeviceListener implementation.
+  virtual void OnDeviceChange() OVERRIDE;
+
  protected:
   virtual ~AudioManagerWin();
 
+  // Implementation of AudioManager.
+  virtual void InitializeOnAudioThread() OVERRIDE;
+
  private:
   enum EnumerationType {
     kUninitializedEnumeration = 0,
@@ -70,6 +80,9 @@ class MEDIA_EXPORT AudioManagerWin : public AudioManagerBase {
       const AudioParameters& params,
       const std::string& device_id);
 
+  // Listen for output device changes.
+  scoped_ptr<AudioDeviceListenerWin> output_device_listener_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerWin);
 };