Remove file-level 'use strict' from file_manager.

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 = {};
 
 var initializeQueue = new AsyncUtil.Queue();
 
 // Initializes the strings. This needs for the volume manager.
 initializeQueue.run(function(fulfill) {
   chrome.fileManagerPrivate.getStrings(function(stringData) {
@@ skipping 88 matching lines @@
   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);
   });
 }