Files.app Test: check the cast icon in drive volume

ui/file_manager/video_player/js/background.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';
 
 // Stores the app windows OLNY for test purpose.
 // We SHOULD NOT use it as it is except for test, since the files which have
 // the same name will be overridden each other.
 var appWindowsForTest = {};
@@ skipping 66 matching lines @@
       frame: 'none',
       singleton: false,
       minWidth: 480,
       minHeight: 270
     },
     fulfill);
   }).then(function(createdWindow) {
     // Stores the window for test purpose.
     appWindowsForTest[videos[0].entry.name] = createdWindow;
 
+    createdWindow.contentWindow.videos = videos;
     createdWindow.setIcon('images/icon/video-player-64.png');
-    createdWindow.contentWindow.videos = videos;
+
+    if (chrome.test) {
+      createdWindow.contentWindow.loadMockCastExtensionForTest = true;
+    }
+
     chrome.runtime.sendMessage({ready: true}, function() {});
   }).catch(function(error) {
     console.error('Launch failed', error.stack || error);
     return Promise.reject(error);
   });
 }
 
 // If is is run in the browser test, wait for the test resources are installed
 // as a component extension, and then load the test resources.
 if (chrome.test) {
   window.testExtensionId = 'ljoplibgfehghmibaoaepfagnmbbfiga';
   chrome.runtime.onMessageExternal.addListener(function(message) {
     if (message.name !== 'testResourceLoaded')
       return;
     var script = document.createElement('script');
     script.src =
         'chrome-extension://' + window.testExtensionId +
         '/common/test_loader.js';
     document.documentElement.appendChild(script);
   });
 }