Begin adding support for tab mirroring via the MediaStream audio/video capturing

content/browser/renderer_host/media/audio_input_device_manager.h

Index: content/browser/renderer_host/media/audio_input_device_manager.h
diff --git a/content/browser/renderer_host/media/audio_input_device_manager.h b/content/browser/renderer_host/media/audio_input_device_manager.h
index 3f0b34c451f46cd043ab744b1d78ab7d60d7ca0c..bdfd77821646d2531f2776ca1711079e1a47a214 100644
--- a/content/browser/renderer_host/media/audio_input_device_manager.h
+++ b/content/browser/renderer_host/media/audio_input_device_manager.h
@@ -29,16 +29,15 @@ namespace media_stream {
 
 class AudioInputDeviceManagerEventHandler;
 
-class CONTENT_EXPORT AudioInputDeviceManager
-    : public base::RefCountedThreadSafe<AudioInputDeviceManager>,
-      public MediaStreamProvider {
+class CONTENT_EXPORT AudioInputDeviceManager : public MediaStreamProvider {
  public:
   // Calling Start() with this kFakeOpenSessionId will open the default device,
   // even though Open() has not been called. This is used to be able to use the
   // AudioInputDeviceManager before MediaStream is implemented.
   static const int kFakeOpenSessionId;
 
-  explicit AudioInputDeviceManager(media::AudioManager* audio_manager);
+  AudioInputDeviceManager(media::AudioManager* audio_manager,
+                          media_stream::MediaStreamType device_type);
 
   // MediaStreamProvider implementation, called on IO thread.
   virtual void Register(MediaStreamProviderListener* listener,
@@ -56,7 +55,6 @@ class CONTENT_EXPORT AudioInputDeviceManager
   void Stop(int session_id);
 
  private:
-  friend class base::RefCountedThreadSafe<AudioInputDeviceManager>;
   virtual ~AudioInputDeviceManager();
 
   // Executed on media stream device thread.
@@ -71,6 +69,10 @@ class CONTENT_EXPORT AudioInputDeviceManager
 
   bool IsOnDeviceThread() const;
 
+  // The type of audio input devices managed by this instance (e.g., user
+  // audio capture, tab audio output).
+  const media_stream::MediaStreamType device_type_;
+
   // Only accessed on Browser::IO thread.
   MediaStreamProviderListener* listener_;
   int next_capture_session_id_;