[Chromoting] Move DefaultAudioDeviceChangeDetector out of AudioCapturerWin

remoting/host/audio_capturer_win.h

Index: remoting/host/audio_capturer_win.h
diff --git a/remoting/host/audio_capturer_win.h b/remoting/host/audio_capturer_win.h
index 0019242fc48f2f9646f6260ab617a9a43c0fbf91..9f35a9cda3236889303aa19d856bd105088aafdc 100644
--- a/remoting/host/audio_capturer_win.h
+++ b/remoting/host/audio_capturer_win.h
@@ -22,6 +22,8 @@
 
 namespace remoting {
 
+class DefaultAudioDeviceChangeDetector;
+
 class AudioCapturerWin : public AudioCapturer {
  public:
   AudioCapturerWin();
@@ -31,11 +33,6 @@ class AudioCapturerWin : public AudioCapturer {
   bool Start(const PacketCapturedCallback& callback) override;
 
  private:
-  // An IMMNotificationClient implementation to detect the event of default
-  // audio device recently changed. If it indicates a changed happend recently,
-  // we need to recreate all audio components.
-  class MMNotificationClient;
-
   // Executes Deinitialize() and Initialize(). If Initialize() function call
   // returns false, Deinitialize() will be called again to ensure we will
   // initialize COM components again.
@@ -85,7 +82,7 @@ class AudioCapturerWin : public AudioCapturer {
   base::win::ScopedComPtr<IMMDevice> mm_device_;
   base::win::ScopedComPtr<IAudioEndpointVolume> audio_volume_;
 
-  const std::unique_ptr<MMNotificationClient> mm_notification_client_;
+  std::unique_ptr<DefaultAudioDeviceChangeDetector> default_device_detector_;
 
   HRESULT last_capture_error_;