Fixed close button for retina displays in identity approval scope UI

chrome/browser/resources/identity_scope_approval_dialog/scope_approval_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.
 
 var webview;
 
 /**
  * Points the webview to the starting URL of a scope authorization
  * flow, and unhides the dialog once the page has loaded.
  * @param {string} url The url of the authorization entry point.
@@ skipping 29 matching lines @@
   }
 }
 
 document.addEventListener('DOMContentLoaded', function() {
   webview = document.querySelector('webview');
 
   document.querySelector('.titlebar-close-button').onclick = function() {
     window.close();
   };
 
-  chrome.identityPrivate.getResources(function(resources) {
-    var style = document.styleSheets[0];
-
-    function insertRule(selector, url) {
-      style.insertRule(selector + ' { background-image: url(' + url + '); }',
-                       style.cssRules.length);
-    }
-
-    insertRule('.titlebar-close-button', resources.IDR_CLOSE_DIALOG);
-    insertRule('.titlebar-close-button:hover', resources.IDR_CLOSE_DIALOG_H);
-    insertRule('.titlebar-close-button:active', resources.IDR_CLOSE_DIALOG_P);
-
-    document.title = resources.IDS_EXTENSION_PERMISSIONS_PROMPT_TITLE;
+  chrome.identityPrivate.getStrings(function(strings) {
+    document.title = strings['window-title'];
   });
 });