Video Player: Show a checkmark on the currently playing device in cast menu

ui/file_manager/video_player/js/video_player.js

 // Copyright 2014 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.
 
 'use strict';
 
 /**
  * @param {Element} playerContainer Main container.
  * @param {Element} videoContainer Container for the video element.
  * @param {Element} controlsContainer Container for video controls.
@@ skipping 466 matching lines @@
 /**
  * Invokes when a menuitem in the cast menu is selected.
  * @param {Object} cast Selected element in the list of casts.
  */
 VideoPlayer.prototype.onCastSelected_ = function(cast) {
   // If the selected item is same as the current item, do nothing.
   if ((this.currentCast_ && this.currentCast_.label) === (cast && cast.label))
     return;
 
   this.currentCast_ = cast || null;
+  this.updateCheckOnCastMenu_();
   this.reloadCurrentVideo();
 };
 
 /**
  * Set the list of casts.
  * @param {Array.<Object>} casts List of casts.
  */
 VideoPlayer.prototype.setCastList = function(casts) {
   var button = document.querySelector('.cast-button');
   var menu = document.querySelector('#cast-menu');
@@ skipping 12 matching lines @@
     var currentCastAvailable = casts.some(function(cast) {
       return this.currentCast_.label === cast.label;
     }.wrap(this));
 
     if (!currentCastAvailable)
       this.onCurrentCastDisappear_();
   }
 
   var item = new cr.ui.MenuItem();
   item.label = loadTimeData.getString('VIDEO_PLAYER_PLAY_THIS_COMPUTER');
+  item.castLabel = '';
   item.addEventListener('activate', this.onCastSelected_.wrap(this, null));
   menu.appendChild(item);
 
   for (var i = 0; i < casts.length; i++) {
     var item = new cr.ui.MenuItem();
     item.label = casts[i].friendlyName;
+    item.castLabel = casts[i].label;
     item.addEventListener('activate',
                           this.onCastSelected_.wrap(this, casts[i]));
     menu.appendChild(item);
   }
+  this.updateCheckOnCastMenu_();
   button.classList.remove('hidden');
 };
 
 /**
+ * Updates the check status of the cast menu items.
+ * @private
+ */
+VideoPlayer.prototype.updateCheckOnCastMenu_ = function() {
+  var menu = document.querySelector('#cast-menu');
+  var menuItems = menu.menuItems;
+  for (var i = 0; i < menuItems.length; i++) {
+    var item = menuItems[i];
+    if (this.currentCast_ === null) {
+      // Playing on this computer.
+      if (item.castLabel === '')
+        item.checked = true;
+      else
+        item.checked = false;
+    } else {
+      // Playing on cast device.
+      if (item.castLabel === this.currentCast_.label)
+        item.checked = true;
+      else
+        item.checked = false;
+    }
+  }
+};
+
+/**
  * Called when the current cast is disappear from the cast list.
  * @private
  */
 VideoPlayer.prototype.onCurrentCastDisappear_ = function() {
   this.currentCast_ = null;
   this.currentSession_ = null;
   this.controls.showErrorMessage('GALLERY_VIDEO_DECODING_ERROR');
   this.unloadVideo();
 };
 
@@ skipping 34 matching lines @@
 var initPromise = Promise.all(
     [new Promise(initVideos.wrap(null)),
      new Promise(initStrings.wrap(null)),
      new Promise(util.addPageLoadHandler.wrap(null))]);
 
 initPromise.then(function(results) {
   var videos = results[0];
   player.prepare(videos);
   return new Promise(player.playFirstVideo.wrap(player));
 }.wrap(null));