Letting Flash join MediaSession (stack implementaion)

content/browser/media/session/media_session.h

Index: content/browser/media/session/media_session.h
diff --git a/content/browser/media/session/media_session.h b/content/browser/media/session/media_session.h
index d791c61eacc54dde1bfc4437a7223ad0be8f1638..832e95cf8bb9596cb68908e2135a759a3c3106b1 100644
--- a/content/browser/media/session/media_session.h
+++ b/content/browser/media/session/media_session.h
@@ -103,8 +103,10 @@ class MediaSession : public WebContentsObserver,
   // |type| represents the origin of the request.
   CONTENT_EXPORT void Stop(SuspendType suspend_type);
 
-  // Change the volume multiplier of the session to |volume_multiplier|.
-  CONTENT_EXPORT void SetVolumeMultiplier(double volume_multiplier);
+  CONTENT_EXPORT void Duck();
+  CONTENT_EXPORT void Unduck();
+
+  CONTENT_EXPORT bool IsDucking() { return is_ducking_; }
 
   // Returns if the session can be controlled by Resume() and Suspend calls
   // above.
@@ -123,6 +125,8 @@ class MediaSession : public WebContentsObserver,
   // Returns if the session is currently suspended or inactive.
   CONTENT_EXPORT bool IsSuspended() const;
 
+  void SetOnTop(bool is_on_top);
+
  private:
   friend class content::WebContentsUserData<MediaSession>;
   friend class ::MediaSessionBrowserTest;
@@ -192,8 +196,15 @@ class MediaSession : public WebContentsObserver,
   RegisterMediaSessionStateChangedCallbackForTest(
       const StateChangedCallback& cb);
 
+  CONTENT_EXPORT bool AddPepperPlayer(MediaSessionObserver* observer,
+                                      int player_id);
+
+  double GetVolumeMultiplier() const;
+  double GetPepperVolumeMultiplier() const;
+
   std::unique_ptr<MediaSessionDelegate> delegate_;
   PlayersMap players_;
+  PlayersMap pepper_players_;
 
   State audio_focus_state_;
   SuspendType suspend_type_;
@@ -201,9 +212,12 @@ class MediaSession : public WebContentsObserver,
 
   MediaSessionUmaHelper uma_helper_;
 
-  // The volume multiplier of this session. All players in this session should
-  // multiply their volume with this multiplier to get the effective volume.
-  double volume_multiplier_;
+  // Whether this session is ducked, which is used to compute the volume
+  // multiplier of this session. All players in this session should multiply
+  // their volume with this multiplier to get the effective volume.
+  bool is_ducking_;
+
+  bool is_on_top_;
 
   MediaMetadata metadata_;
   base::CallbackList<void(State)> media_session_state_listeners_;