[MediaRouter] Update MR-2-Extension's PostMessage to return boolean.

extensions/renderer/resources/media_router_bindings.js

 // 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.
 
 var mediaRouterObserver;
 
 define('media_router_bindings', [
     'mojo/public/js/bindings',
     'mojo/public/js/core',
     'content/public/renderer/service_provider',
@@ skipping 431 matching lines @@
    */
   MediaRouter.prototype.closeRoute = function(routeId) {
     this.handlers_.closeRoute(routeId);
   };
 
   /**
    * Posts a message to the route designated by |routeId|.
    * @param {!string} routeId
    * @param {!string} message
    * @param {string} extraInfoJson
+   * @return {!Promise.<boolean>} Resolved with true if the message was sent,
+   *  or false on failure.
    */
   MediaRouter.prototype.postMessage = function(
       routeId, message, extraInfoJson) {
     // TODO(mfoltz): Remove extraInfoJson if no longer needed.

[mark a. foltz, 2015/06/11 05:04:29]

Is it possible to take care of this now?

[haibinlu, 2015/06/11 17:37:17]

Done.

-    this.handlers_.postMessage(routeId, message, JSON.parse(extraInfoJson));
+    this.handlers_.postMessage(routeId, message, JSON.parse(extraInfoJson))
+        .then(function() {
+          return true;
+        }, function() {
+          return false;
+        });
   };
 
   /**
    * Requests that the provider manager start sending information about active
    * media routes to the Media Router.
    */
   MediaRouter.prototype.startObservingMediaRoutes = function() {
     this.handlers_.startObservingMediaRoutes();
   };
 
   /**
    * Requests that the provider manager stop sending information about active
    * media routes to the Media Router.
    */
   MediaRouter.prototype.stopObservingMediaRoutes = function() {
     this.handlers_.stopObservingMediaRoutes();
   };
 
   mediaRouterObserver = new MediaRouterObserver(connector.bindHandleToProxy(
       serviceProvider.connectToService(
           mediaRouterMojom.MediaRouterObserver.name),
       mediaRouterMojom.MediaRouterObserver));
 
   return mediaRouterObserver;
 });