Files.app: Don't pass {singleton: false} to chrome.app.window.create.

chrome/browser/resources/file_manager/background/js/background.js

 // Copyright (c) 2012 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';
 
 /**
  * Number of runtime errors catched in the background page.
  * @type {number}
  */
@@ skipping 335 matching lines @@
  */
 var FILE_MANAGER_WINDOW_CREATE_OPTIONS = Object.freeze({
   defaultLeft: Math.round(window.screen.availWidth * 0.1),
   defaultTop: Math.round(window.screen.availHeight * 0.1),
   defaultWidth: Math.round(window.screen.availWidth * 0.8),
   defaultHeight: Math.round(window.screen.availHeight * 0.8),
   minWidth: 320,
   minHeight: 240,
   frame: 'none',
   hidden: true,
-  transparentBackground: true,
-  singleton: false
+  transparentBackground: true
 });
 
 /**
  * @param {Object=} opt_appState App state.
  * @param {number=} opt_id Window id.
  * @param {LaunchType=} opt_type Launch type. Default: ALWAYS_CREATE.
  * @param {function(string)=} opt_callback Completion callback with the App ID.
  */
 function launchFileManager(opt_appState, opt_id, opt_type, opt_callback) {
   var type = opt_type || LaunchType.ALWAYS_CREATE;
@@ skipping 140 matching lines @@
  * Audio player window create options.
  * @type {Object}
  * @const
  */
 var AUDIO_PLAYER_CREATE_OPTIONS = Object.freeze({
   type: 'panel',
   hidden: true,
   minHeight: 35 + 58,
   minWidth: 280,
   height: 35 + 58,
-  width: 280,
-  singleton: false
+  width: 280
 });
 
 var audioPlayer = new SingletonAppWindowWrapper('mediaplayer.html',
                                                 AUDIO_PLAYER_CREATE_OPTIONS);
 
 /**
  * Launch the audio player.
  * @param {Object} playlist Playlist.
  */
 function launchAudioPlayer(playlist) {
@@ skipping 123 matching lines @@
     contexts: ['launcher'],
     title: str('NEW_WINDOW_BUTTON_LABEL')
   });
 };
 
 /**
  * Singleton instance of Background.
  * @type {Background}
  */
 window.background = new Background();