Handle audio device changes on Windows.

media/audio/win/audio_device_listener_win.h

Index: media/audio/win/audio_device_listener_win.h
diff --git a/media/audio/win/audio_device_listener_win.h b/media/audio/win/audio_device_listener_win.h
new file mode 100644
index 0000000000000000000000000000000000000000..5eca5fa894cc1039c2c910100c204ddc857dd4c3
--- /dev/null
+++ b/media/audio/win/audio_device_listener_win.h
@@ -0,0 +1,51 @@
+// 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_DEVICE_LISTENER_WIN_H_
+#define MEDIA_AUDIO_WIN_AUDIO_DEVICE_LISTENER_WIN_H_
+
+#include <MMDeviceAPI.h>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/win/scoped_comptr.h"
+#include "media/audio/audio_manager.h"
+#include "media/base/media_export.h"
+
+using base::win::ScopedComPtr;
+
+namespace media {
+
+// IMMNotificationClient implementation for listening for default device changes
+// and forwarding to AudioManagerBase so it can notify downstream clients.

[scherkus (not reviewing), 2012/10/23 02:23:11]

s/AudioManagerWin/?

[DaleCurtis, 2012/10/24 00:09:27]

Done.

+// TODO(henrika): Refactor based on upcoming CoreAudioUtil class for windows.
+class MEDIA_EXPORT AudioDeviceListenerWin : public IMMNotificationClient {
+ public:
+  // AudioDeviceListener::OnDeviceChanged() will be called from an system level
+  // multimedia thread.  As such the callee should be thread safe.
+  explicit AudioDeviceListenerWin(AudioManager::AudioDeviceListener* listener);
+  virtual ~AudioDeviceListenerWin();
+
+ private:
+  ULONG __stdcall AddRef();

[scherkus (not reviewing), 2012/10/23 02:23:11]

nit: add "IMMNotificationClient implementation." comment

do these also need to be virtual and OVERRIDE?

[DaleCurtis, 2012/10/23 03:28:20]

I dunno, this compiles and runs fine though. Henrik?

[henrika (OOO until Aug 14), 2012/10/23 08:21:43]

I vote for COM style and use what's in there. Taken care of in the COM macros.
No need to rewrite if you ask me.

[scherkus (not reviewing), 2012/10/23 17:48:19]

Yeah it looks like the tide has turned in favour of the COM methods. I don't
really mind either way.

[DaleCurtis, 2012/10/23 20:09:08]

Will change back in the next revision.

+  ULONG __stdcall Release();
+  HRESULT __stdcall QueryInterface(REFIID iid, void** object);
+  HRESULT __stdcall OnPropertyValueChanged(LPCWSTR device_id,
+                                           const PROPERTYKEY key);
+  HRESULT __stdcall OnDeviceAdded(LPCWSTR device_id);
+  HRESULT __stdcall OnDeviceRemoved(LPCWSTR device_id);
+  HRESULT __stdcall OnDeviceStateChanged(LPCWSTR device_id, DWORD new_state);
+  HRESULT __stdcall OnDefaultDeviceChanged(EDataFlow flow, ERole role,
+                                           LPCWSTR new_default_device_id);
+
+  AudioManager::AudioDeviceListener* listener_;
+  ScopedComPtr<IMMDeviceEnumerator> device_enumerator_;
+  std::string default_device_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioDeviceListenerWin);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_WIN_AUDIO_DEVICE_LISTENER_WIN_H_