Implement MediaSession on top of the WebMediaPlayerDelegate.

content/renderer/media/android/webmediaplayer_android.h

Index: content/renderer/media/android/webmediaplayer_android.h
diff --git a/content/renderer/media/android/webmediaplayer_android.h b/content/renderer/media/android/webmediaplayer_android.h
index 6fa9ca5b49808df3e22c6d7bbb5d2bd53d312513..04d3a9f00f78a97d1e1b8291b4be5ba78fd66de6 100644
--- a/content/renderer/media/android/webmediaplayer_android.h
+++ b/content/renderer/media/android/webmediaplayer_android.h
@@ -18,7 +18,6 @@
 #include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "cc/layers/video_frame_provider.h"
-#include "content/public/renderer/render_frame_observer.h"
 #include "content/renderer/media/android/media_info_loader.h"
 #include "content/renderer/media/android/media_source_delegate.h"
 #include "content/renderer/media/android/renderer_media_player_manager.h"
@@ -29,6 +28,7 @@
 #include "media/base/demuxer_stream.h"
 #include "media/base/media_keys.h"
 #include "media/base/time_delta_interpolator.h"
+#include "media/blink/webmediaplayer_delegate.h"
 #include "media/blink/webmediaplayer_params.h"
 #include "media/cdm/proxy_decryptor.h"
 #include "third_party/WebKit/public/platform/WebGraphicsContext3D.h"
@@ -66,7 +66,6 @@ class CdmFactory;
 class MediaLog;
 class MediaPermission;
 class WebContentDecryptionModuleImpl;
-class WebMediaPlayerDelegate;
 }
 
 namespace content {
@@ -78,11 +77,12 @@ class RendererMediaPlayerManager;
 // media player in the browser process. It listens to all the status changes
 // sent from the browser process and sends playback controls to the media
 // player.
-class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
-                              public cc::VideoFrameProvider,
-                              public RenderFrameObserver,
-                              public StreamTextureFactoryContextObserver,
-                              public media::RendererMediaPlayerInterface {
+class WebMediaPlayerAndroid
+    : public blink::WebMediaPlayer,
+      public cc::VideoFrameProvider,
+      public StreamTextureFactoryContextObserver,
+      public media::RendererMediaPlayerInterface,
+      public NON_EXPORTED_BASE(media::WebMediaPlayerDelegate::Observer) {
  public:
   // Construct a WebMediaPlayerAndroid object. This class communicates with the
   // MediaPlayerAndroid object in the browser process through |proxy|.
@@ -226,9 +226,6 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   // However, the actual GlTexture is not released to keep the video screenshot.
   void SuspendAndReleaseResources() override;
 
-  // RenderFrameObserver implementation.
-  void OnDestruct() override;
-
 #if defined(VIDEO_HOLE)
   // Calculate the boundary rectangle of the media player (i.e. location and
   // size of the video frame).
@@ -272,6 +269,13 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   // is not available.
   void OnWaitingForDecryptionKey() override;
 
+  // WebMediaPlayerDelegate::Observer implementation.
+  void OnHidden() override;
+  void OnShown() override;
+  void OnPlay() override;
+  void OnPause() override;
+  void OnVolumeMultiplierUpdate(double multiplier) override;
+
  protected:
   // Helper method to update the playing state.
   void UpdatePlayingState(bool is_playing_);
@@ -544,6 +548,12 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   // Whether to delete the existing texture and re-create it.
   bool suppress_deleting_texture_;
 
+  // Whether OnPlaybackComplete() has been called since the last playback.
+  bool playback_completed_;
+
+  double volume_;
+  double volume_multiplier_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebMediaPlayerAndroid> weak_factory_;