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

chrome/browser/resources/print_preview/color_settings.js

Index: chrome/browser/resources/print_preview/color_settings.js
diff --git a/chrome/browser/resources/print_preview/color_settings.js b/chrome/browser/resources/print_preview/color_settings.js
index f0f6885a90543f358b541faa0f34f90eb3d15625..c3d7328259613b399b6d83757254bde011c09271 100644
--- a/chrome/browser/resources/print_preview/color_settings.js
+++ b/chrome/browser/resources/print_preview/color_settings.js
@@ -62,13 +62,14 @@ cr.define('print_preview', function() {
       this.bwRadioButton_.onclick = function() {
         setColor(false);
       };
-      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) {
@@ -97,7 +98,7 @@ cr.define('print_preview', function() {
     },
 
     /**
-     * Executes when a PDFLoaded event occurs.
+     * Executes when a |customEvents.PDF_LOADED| event occurs.
      * @private
      */
     onPDFLoaded_: function() {