Letting Flash join MediaSession (stack implementaion)

content/browser/media/session/media_session.h

 // Copyright 2015 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 CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 
 #include <stddef.h>
 
 #include "base/callback_list.h"
@@ skipping 45 matching lines @@
     // Suspended by the page via script or user interaction.
     CONTENT,
   };
 
   // Returns the MediaSession associated to this WebContents. Creates one if
   // none is currently available.
   CONTENT_EXPORT static MediaSession* Get(WebContents* web_contents);
 
   ~MediaSession() override;
 
+  void WasShown() override;

[mlamouri (slow - plz ping), 2016/09/05 09:40:36]

To simplify understanding this, can you explain why you are doing this?

[Zhiqiang Zhang (Slow), 2016/09/05 09:54:21]

Oh, it seems like the code when I was doing experimental which gives audio focus
to a tab when the tab is brought to front.

Will remove this.

+
   void SetMetadata(const MediaMetadata& metadata);
   const MediaMetadata& metadata() const { return metadata_; }
 
   // Adds the given player to the current media session. Returns whether the
   // player was successfully added. If it returns false, AddPlayer() should be
   // called again later.
   CONTENT_EXPORT bool AddPlayer(MediaSessionObserver* observer,
                                 int player_id,
                                 media::MediaContentType media_content_type);
 
@@ skipping 28 matching lines @@
   CONTENT_EXPORT void Stop(SuspendType suspend_type);
 
   // Let the media session start ducking such that the volume multiplier is
   // reduced.
   CONTENT_EXPORT void StartDucking();
 
   // Let the media session stop ducking such that the volume multiplier is
   // 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;
 
   // Returns if the session is currently active.
   CONTENT_EXPORT bool IsActive() const;
 
   // Returns if the session is currently suspended.
   // TODO(mlamouri): IsSuspended() below checks if the state is not ACTIVE
   // instead of checking if the state is SUSPENDED. In order to not have to
   // change all the callers and make the current refactoring ridiculously huge,
   // this method is introduced temporarily and will be removed later.
   bool IsReallySuspended() const;
 
   // Returns if the session is currently suspended or inactive.
   CONTENT_EXPORT bool IsSuspended() const;
 
+  void SetOnTop(bool is_on_top);

[mlamouri (slow - plz ping), 2016/09/05 09:40:36]

ditto, what's `SetOnTop` for?

[Zhiqiang Zhang (Slow), 2016/09/05 09:54:21]

I discussed this with Anton, and the method is actually something like
"DuckPepper(bool is_duck)"

+
  private:
   friend class content::WebContentsUserData<MediaSession>;
   friend class ::MediaSessionBrowserTest;
   friend class content::MediaSessionVisibilityBrowserTest;
   friend class content::AudioFocusManagerTest;
   friend class content::MediaSessionStateObserver;
 
   CONTENT_EXPORT void SetDelegateForTests(
       std::unique_ptr<MediaSessionDelegate> delegate);
   CONTENT_EXPORT bool IsActiveForTest() const;
@@ skipping 50 matching lines @@
   // Internal method that should be used instead of setting audio_focus_state_.
   // It sets audio_focus_state_ and notifies observers about the state change.
   void SetAudioFocusState(State audio_focus_state);
 
   // Update the volume multiplier when ducking state changes.
   void UpdateVolumeMultiplier();
 
   // 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_;
   AudioFocusManager::AudioFocusType audio_focus_type_;
 
   MediaSessionUmaHelper uma_helper_;
 
   // The ducking state of this media session. The initial value is |false|, and
   // is set to |true| after StartDucking(), and will be set to |false| after
   // StopDucking().
   bool is_ducking_;
+  bool is_on_top_;
 
   MediaMetadata metadata_;
   base::CallbackList<void(State)> media_session_state_listeners_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSession);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_