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

third_party/WebKit/Source/modules/mediasession/MediaSession.idl

 // 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.
 
+// https://wicg.github.io/mediasession/#enumdef-mediasessionplaybackstate
+
+enum MediaSessionPlaybackState {
+    "none",
+    "paused",
+    "playing"
+};
+
 // https://wicg.github.io/mediasession/#the-mediasession-interface
 
 [
     RuntimeEnabled=MediaSession,
 ] interface MediaSession : EventTarget {
     attribute MediaMetadata? metadata;
 
+    attribute MediaSessionPlaybackState playbackState;
+
     attribute EventHandler onplay;
     attribute EventHandler onpause;
-    attribute EventHandler onplaypause;
     attribute EventHandler onprevioustrack;
     attribute EventHandler onnexttrack;
     attribute EventHandler onseekforward;
     attribute EventHandler onseekbackward;
 };