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 9d501fcfd8b7324f41eaf052962620b96e4c43fb..ce800125d895e796ec948caa697cfa7b6f8710b4 100644
--- a/content/browser/media/session/media_session.h
+++ b/content/browser/media/session/media_session.h
@@ -63,6 +63,8 @@ class MediaSession : public WebContentsObserver,
 
   ~MediaSession() override;
 
+  void WasShown() override;
+
   void SetMetadata(const MediaMetadata& metadata);
   const MediaMetadata& metadata() const { return metadata_; }
 
@@ -111,6 +113,8 @@ class MediaSession : public WebContentsObserver,
   // recovered.
   CONTENT_EXPORT void StopDucking();
 
+  CONTENT_EXPORT bool IsDucking() { return is_ducking_; }
+
   // Returns if the session can be controlled by Resume() and Suspend calls
   // above.
   CONTENT_EXPORT bool IsControllable() const;
@@ -128,6 +132,11 @@ class MediaSession : public WebContentsObserver,
   // Returns if the session is currently suspended or inactive.
   CONTENT_EXPORT bool IsSuspended() const;
 
+  void AllowPepperOverrideDucking();
+  void DisallowPepperOverrideDucking();
+
+  bool HasPepper() const;
+
  private:
   friend class content::WebContentsUserData<MediaSession>;
   friend class ::MediaSessionBrowserTest;
@@ -198,14 +207,19 @@ class MediaSession : public WebContentsObserver,
   // Get the volume multiplier, which depends on whether the media session is
   // ducking.
   double GetVolumeMultiplier() const;
+  double GetPepperVolumeMultiplier() const;
 
   // Registers a MediaSession state change callback.
   CONTENT_EXPORT std::unique_ptr<base::CallbackList<void(State)>::Subscription>
   RegisterMediaSessionStateChangedCallbackForTest(
       const StateChangedCallback& cb);
 
+  CONTENT_EXPORT bool AddPepperPlayer(MediaSessionObserver* observer,
+                                      int player_id);
+
   std::unique_ptr<MediaSessionDelegate> delegate_;
   PlayersMap players_;
+  PlayersMap pepper_players_;
 
   State audio_focus_state_;
   SuspendType suspend_type_;
@@ -217,6 +231,9 @@ class MediaSession : public WebContentsObserver,
   // is set to |true| after StartDucking(), and will be set to |false| after
   // StopDucking().
   bool is_ducking_;
+  // Whether allow pepper to override ducking (play in full volume) when the
+  // session is not active.
+  bool allow_pepper_override_ducking_;
 
   MediaMetadata metadata_;
   base::CallbackList<void(State)> media_session_state_listeners_;