Listen to the audio focus event for MSE/EME

media/base/android/media_player_android.h

 // Copyright (c) 2013 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 MEDIA_BASE_ANDROID_MEDIA_PLAYER_ANDROID_H_
 #define MEDIA_BASE_ANDROID_MEDIA_PLAYER_ANDROID_H_
 
 #include <jni.h>
 #include <string>
 
 #include "base/callback.h"
+#include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
+#include "media/base/android/media_player_listener.h"
 #include "media/base/media_export.h"
 #include "ui/gl/android/scoped_java_surface.h"
 #include "url/gurl.h"
 
 namespace media {
 
 class BrowserCdm;
 class MediaPlayerManager;
 
 // This class serves as the base class for different media player
@@ skipping 56 matching lines @@
   int player_id() { return player_id_; }
 
   GURL frame_url() { return frame_url_; }
 
  protected:
   MediaPlayerAndroid(int player_id,
                      MediaPlayerManager* manager,
                      const RequestMediaResourcesCB& request_media_resources_cb,
                      const GURL& frame_url);
 
+  // TODO(qinmin): Simplify the MediaPlayerListener class to only listen to
+  // media interrupt events. And have a separate child class to listen to all
+  // the events needed by MediaPlayerBridge. http://crbug.com/422597.
+  // MediaPlayerListener callbacks.
+  virtual void OnVideoSizeChanged(int width, int height);
+  virtual void OnMediaError(int error_type);
+  virtual void OnBufferingUpdate(int percent);
+  virtual void OnPlaybackComplete();
+  virtual void OnMediaInterrupted();
+  virtual void OnSeekComplete();
+  virtual void OnMediaPrepared();
+
+  // Attach/Detaches |listener_| for listening to all the events.
+  void AttachListener(jobject j_media_player);

[xhwang, 2014/10/14 18:23:30]

It seems |j_media_player| can be NULL here. What does it mean to have a null or
non-null |j_media_player|? It's not obvious that the |j_media_player| can also
listen to those events directly. Some comments would be helpful.

[qinmin, 2014/10/14 21:55:51]

Done.

+  void DetachListener();
+
   MediaPlayerManager* manager() { return manager_; }
 
   RequestMediaResourcesCB request_media_resources_cb_;
 
  private:
+  friend class MediaPlayerListener;
+
   // Player ID assigned to this player.
   int player_id_;
 
   // Resource manager for all the media players.
   MediaPlayerManager* manager_;
 
   // Url for the frame that contains this player.
   GURL frame_url_;
 
+  // Listener object that listens to all the media player events.
+  scoped_ptr<MediaPlayerListener> listener_;
+
+  // Weak pointer passed to |listener_| for callbacks.
+  // NOTE: Weak pointers must be invalidated before all other member variables.
+  base::WeakPtrFactory<MediaPlayerAndroid> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaPlayerAndroid);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_ANDROID_MEDIA_PLAYER_ANDROID_H_