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

third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js

Index: third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js
diff --git a/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js b/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js
index b67c1d8cc370a73c027095f8261bb6b0af9dd02e..2a73642973109c1ceb3ad19deacc377c2de70fb3 100644
--- a/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js
+++ b/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/mediasessionservice-mock.js
@@ -5,6 +5,7 @@
 "use strict";
 
 var MediaSessionAction;
+var MediaSessionPlaybackState;
 
 function mojoString16ToJS(mojoString16) {
   return String.fromCharCode.apply(null, mojoString16.data);
@@ -46,6 +47,7 @@ let mediaSessionServiceMock = loadMojoModules(
       let [mediaSessionService, router] = mojo.modules;
 
       MediaSessionAction = mediaSessionService.MediaSessionAction;
+      MediaSessionPlaybackState = mediaSessionService.MediaSessionPlaybackState;
 
       class MediaSessionServiceMock {
         constructor(interfaceProvider) {
@@ -71,6 +73,15 @@ let mediaSessionServiceMock = loadMojoModules(
           this.metadataCallback_ = callback;
         }
 
+        setPlaybackState(state) {
+          if (!!this.setPlaybackStateCallback_)
+            this.setPlaybackStateCallback_(state);
+        }
+
+        setPlaybackStateCallback(callback) {
+          this.setPlaybackStateCallback_ = callback;
+        }
+
         enableAction(action) {
           if (!!this.enableDisableActionCallback_)
             this.enableDisableActionCallback_(action, true);