[Files.app] Split the JavaScript files into subdirectories: common, background, and foreground

chrome/browser/resources/file_manager/foreground/js/error_dialog.js

 // Copyright 2013 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 {HTMLElement} parentNode Node to be parent for this dialog.
  * @constructor
  */
 function ErrorDialog(parentNode) {
   cr.ui.dialogs.BaseDialog.call(this, parentNode);
 }
 
 ErrorDialog.prototype = {
   __proto__: cr.ui.dialogs.BaseDialog.prototype
 };
 
 /**
  * One-time initialization of DOM.
  * @private
  */
 ErrorDialog.prototype.initDom_ = function() {
   cr.ui.dialogs.BaseDialog.prototype.initDom_.call(this);
   this.frame_.classList.add('error-dialog-frame');
   var img = this.document_.createElement('div');
   img.className = 'error-dialog-img';
   this.frame_.insertBefore(img, this.text_);
 };