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

chrome/browser/resources/print_preview/layout_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 LayoutSettings object. This object encapsulates all settings and
    * logic related to layout mode (portrait/landscape).
@@ skipping 51 matching lines @@
     },
 
     /**
      * Adding listeners to all layout related controls. The listeners take care
      * of altering their behavior depending on |hasPendingPreviewRequest|.
      * @private
      */
     addEventListeners_: function() {
       this.landscapeRadioButton_.onclick = this.onLayoutButtonClick_.bind(this);
       this.portraitRadioButton_.onclick = this.onLayoutButtonClick_.bind(this);
-      document.addEventListener('PDFLoaded', this.onPDFLoaded_.bind(this));
-      document.addEventListener('printerCapabilitiesUpdated',
+      document.addEventListener(customEvents.PDF_LOADED,
+                                this.onPDFLoaded_.bind(this));
+      document.addEventListener(customEvents.PRINTER_CAPABILITIES_UPDATED,
                                 this.onPrinterCapabilitiesUpdated_.bind(this));
     },
 
     /**
-     * Listener triggered when a printerCapabilitiesUpdated event occurs.
+     * Executes when a |customEvents.PRINTER_CAPABILITIES_UPDATED| event occurs.
      * @private
      */
     onPrinterCapabilitiesUpdated_: function(e) {
       if (e.printerCapabilities.disableLandscapeOption)
         this.fadeInOut_(e.printerCapabilities.disableLandscapeOption);
     },
 
     /**
      * Listener executing when |this.landscapeRadioButton_| or
      * |this.portraitRadioButton_| is clicked.
      * @private
      */
     onLayoutButtonClick_: function() {
       // If the chosen layout is same as before, nothing needs to be done.
       if (this.hasChanged_())
         setDefaultValuesAndRegeneratePreview(true);
     },
 
     /**
-     * Listener executing when a PDFLoaded event occurs.
+     * Listener executing when a |customEvents.PDF_LOADED| event occurs.
      * @private
      */
     onPDFLoaded_: function() {
       this.fadeInOut_(!previewModifiable);
     },
 
     /**
      * @param {boolean} fadeOut True if |this.layoutOption_| should be faded
      *     out, false if it should be faded in.
      * @private
      */
     fadeInOut_: function(fadeOut) {
       fadeOut ? fadeOutElement(this.layoutOption_) :
           fadeInElement(this.layoutOption_);
     }
   };
 
   return {
     LayoutSettings: LayoutSettings,
   };
 });