Only set throbber visibility for throbbers in the Sync setup overlay.

chrome/browser/resources/sync_setup_overlay.js

 // Copyright (c) 2012 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('options', function() {
   /** @const */ var OptionsPage = options.OptionsPage;
 
   // True if the synced account uses a custom passphrase.
   var usePassphrase_ = false;
 
@@ skipping 633 matching lines @@
       else if (page == 'timeout')
         this.showTimeoutPage_();
     },
 
     /**
      * Changes the visibility of throbbers on this page.
      * @param {boolean} visible Whether or not to set all throbber nodes
      *     visible.
      */
     setThrobbersVisible_: function(visible) {
-      var throbbers = document.getElementsByClassName('throbber');
+      var throbbers = this.pageDiv.getElementsByClassName('throbber');
       for (var i = 0; i < throbbers.length; i++)
         throbbers[i].style.visibility = visible ? 'visible' : 'hidden';
     },
 
     /**
      * Reset the state of all descendant elements of a root element to their
      * initial state.
      * The initial state is specified by adding a class to the descendant
      * element in sync_setup_overlay.html.
      * @param {HTMLElement} pageElementId The root page element id.
@@ skipping 98 matching lines @@
 
   SyncSetupOverlay.showStopSyncingUI = function() {
     SyncSetupOverlay.getInstance().showStopSyncingUI_();
   };
 
   // Export
   return {
     SyncSetupOverlay: SyncSetupOverlay
   };
 });