[ChromeOS] Update login.js to use disableTextSelectAndDrag.

chrome/browser/resources/chromeos/login/login.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.
 
 /**
  * @fileoverview Login UI based on a stripped down OOBE controller.
  * TODO(xiyuan): Refactoring this to get a better structure.
  */
 
 var localStrings = new LocalStrings();
@@ skipping 131 matching lines @@
   };
 
   // Export
   return {
     Oobe: Oobe
   };
 });
 
 var Oobe = cr.ui.Oobe;
 
-// Disable text selection.
-document.onselectstart = function(e) {
-  e.preventDefault();
-}
-
-// Disable dragging.
-document.ondragstart = function(e) {
-  e.preventDefault();
-}
+disableTextSelectAndDrag();
 
 document.addEventListener('DOMContentLoaded', cr.ui.Oobe.initialize);