arc: avoid checkbox AutomationNode issue

chrome/browser/resources/chromeos/arc_support/background.js

 // Copyright 2016 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.
 
 /**
  * UI Pages. Note the order must be in sync with the ArcAuthService::UIPage
  * enum.
  * @type {Array<string>}
  */
 var UI_PAGES = ['none',
@@ skipping 131 matching lines @@
 /**
  * Sets current metrics mode.
  * @param {string} text Describes current metrics state.
  * @param {boolean} canEnable Defines if user is allowed to change this metrics
  *                            option.
  * @param {boolean} on Defines if metrics are active currently.
  */
 function setMetricsMode(text, canEnable, on) {
   var doc = appWindow.contentWindow.document;
   var enableMetrics = doc.getElementById('enable-metrics');
-  var enableMetricsContainer = doc.getElementById('enable-metrics-container');
-  enableMetricsContainer.hidden = !canEnable;
+  enableMetrics.hidden = !canEnable;
   enableMetrics.checked = on;
 
   var onSettings = function(event) {
     chrome.browser.openTab({'url': 'chrome://settings'}, function() {});
     event.preventDefault();
   };
 
   doc.getElementById('text-metrics').innerHTML = text;
   doc.getElementById('settings-link').addEventListener('click', onSettings);
   doc.getElementById('learn-more-link-metrics').addEventListener('click',
@@ skipping 398 matching lines @@
       type: 'chrome',
       color: '#ffffff'
     },
     'innerBounds': {
       'width': INNER_WIDTH,
       'height': INNER_HEIGHT
     }
   };
   chrome.app.window.create('main.html', options, onWindowCreated);
 });