[MediaSession] Add playbackState attribute to Blink MediaSession and use it to determine playback s…

third_party/WebKit/public/platform/modules/mediasession/media_session.mojom

 // Copyright 2016 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.
 
 module blink.mojom;
 
 import "mojo/common/string16.mojom";
 import "ui/gfx/geometry/mojo/geometry.mojom";
 import "url/mojo/url.mojom";
 
 // Spec: https://wicg.github.io/mediasession/
 enum MediaSessionAction {
      PLAY,
      PAUSE,
-     PLAY_PAUSE,
      PREVIOUS_TRACK,
      NEXT_TRACK,
      SEEK_BACKWARD,
      SEEK_FORWARD,
 
      LAST = SEEK_FORWARD,
 };
 
+enum MediaSessionPlaybackState {
+     NONE,
+     PAUSED,
+     PLAYING,
+};
+
 // Album art in MediaMetadata
 // Spec: https://wicg.github.io/mediasession/
 struct MediaImage {
   url.mojom.Url src;
   mojo.common.mojom.String16 type;
   array<gfx.mojom.Size> sizes;
 };
 
 // MediaMetadata
 // Spec: https://wicg.github.io/mediasession/
 struct MediaMetadata {
   mojo.common.mojom.String16 title;
   mojo.common.mojom.String16 artist;
   mojo.common.mojom.String16 album;
   array<MediaImage> artwork;
 };
 
 interface MediaSessionClient {
   // Notifies the Blink side that a MediaSessionAction has been fired from the
   // UI or the platform.
   DidReceiveAction(MediaSessionAction action);
 };
 
 interface MediaSessionService {
   // MediaSessionClient interface is used to notify Blink MediaSession of
   // media control actions.
   SetClient(MediaSessionClient client);
 
+  // Notifies the browser that the page specified its current playback state.
+  SetPlaybackState(MediaSessionPlaybackState state);
+
   // Notifies the browser that the metadata is set, |metadata| will be displayed
   // on the UI.
   SetMetadata(MediaMetadata? metadata);
 
   // Notifies the browser that the event handler for |action| has been set,
   // browser needs to show a media button in the UI or register listeners to the
   // platform.
   EnableAction(MediaSessionAction action);
   // Notifies the browser that the event handler for |action| has been set,
   // browser needs to hide the media button in the UI and unregister listeners
   // from the platform.
   DisableAction(MediaSessionAction action);
 };