[MD WebUI] Move icons used in Bookmarks and Settings to shared file.

chrome/browser/resources/settings/basic_page/basic_page.js

 // Copyright 2015 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
  * 'settings-basic-page' is the settings page containing the actual settings.
  */
 Polymer({
   is: 'settings-basic-page',
@@ skipping 165 matching lines @@
   showAdvancedSettings_: function(visibility) {
     return visibility !== false;
   },
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Icon name.
    * @private
    */
   getArrowIcon_: function(opened) {
-    return opened ? 'settings:arrow-drop-up' : 'cr:arrow-drop-down';
+    return opened ? 'cr:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 });