MD History: fix script errors when navigating to /syncedTabs (or refreshing)

chrome/browser/resources/history/other_devices.js

 // Copyright (c) 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.
 
 /**
  * @fileoverview The section of the history page that shows tabs from sessions
                  on other devices.
  */
 
 ///////////////////////////////////////////////////////////////////////////////
@@ skipping 567 matching lines @@
   // Create the context menu that appears when the user right clicks
   // on a device name or hit click on the button besides the device name
   document.body.appendChild(DeviceContextMenuController.getInstance().menu);
 
   var doSearch = function(e) {
     devicesView.setSearchText($('search-field').value);
   };
   $('search-field').addEventListener('search', doSearch);
   $('search-button').addEventListener('click', doSearch);
 
-  cr.addWebUIListener('sign-in-state-updated', updateSignInState);
-
   chrome.send('otherDevicesInitialized');
 }
 
 // Add handlers to HTML elements.
 document.addEventListener('DOMContentLoaded', load);