Print Preview Cleanup: Creating enum with all custom events used.

chrome/browser/resources/print_preview/header_footer_settings.js

 // Copyright (c) 2011 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.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Creates a HeaderFooterSettings object. This object encapsulates all
    * settings and logic related to the headers and footers checkbox.
@@ skipping 24 matching lines @@
       return this.headerFooterCheckbox_.checked;
     },
 
     /**
      * Adding listeners to header footer related controls.
      * @private
      */
     addEventListeners_: function() {
       this.headerFooterCheckbox_.onclick =
           this.onHeaderFooterChanged_.bind(this);
-      document.addEventListener('PDFLoaded', this.onPDFLoaded_.bind(this));
+      document.addEventListener(customEvents.PDF_LOADED,
+                                this.onPDFLoaded_.bind(this));
     },
 
     /**
      * Listener executing when the user selects or de-selects the headers
      * and footers option.
      * @private
      */
     onHeaderFooterChanged_: function() {
       requestPrintPreview();
     },
 
     /**
-     * Listener executing when a PDFLoaded event occurs.
+     * Listener executing when a |customEvents.PDF_LOADED| event occurs.
      * @private
      */
     onPDFLoaded_: function() {
       if (!previewModifiable) {
         fadeOutElement(this.headerFooterOption_);
         this.headerFooterCheckbox_.checked = false;
       }
     },
   };
 
   return {
     HeaderFooterSettings: HeaderFooterSettings,
   };
 });