NOT FOR LANDING Implement WebMediaSession

content/browser/media/android/media_session.h

Index: content/browser/media/android/media_session.h
diff --git a/content/browser/media/android/media_session.h b/content/browser/media/android/media_session.h
index fa727b0b049a3a0c2d270df1e3ab7feed1201b21..6503695796de2295b4c1f031a37c96c74ada8674 100644
--- a/content/browser/media/android/media_session.h
+++ b/content/browser/media/android/media_session.h
@@ -47,8 +47,15 @@ class CONTENT_EXPORT MediaSession
   // none is currently available.
   static MediaSession* Get(WebContents* web_contents);
 
+  // Returns a newly created standalone media session.
+  static MediaSession* Create(WebContents* web_contents, int session_id);
+
   ~MediaSession() override;
 
+  bool Activate();
+  void Deactivate();
+  int session_id() const { return session_id_; }
+
   // 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.
@@ -140,7 +147,7 @@ class CONTENT_EXPORT MediaSession
   };
   using PlayersMap = base::hash_set<PlayerIdentifier, PlayerIdentifier::Hash>;
 
-  explicit MediaSession(WebContents* web_contents);
+  MediaSession(WebContents* web_contents, int session_id = 0);
 
   // Setup the JNI.
   void Initialize();
@@ -170,6 +177,7 @@ class CONTENT_EXPORT MediaSession
   State audio_focus_state_;
   SuspendType suspend_type_;
   Type audio_focus_type_;
+  int session_id_;
 
   MediaSessionUmaHelper uma_helper_;