Introduce StickyKeys settings item with behind flag.

chrome/browser/resources/options/browser_options.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() {
   var OptionsPage = options.OptionsPage;
   var ArrayDataModel = cr.ui.ArrayDataModel;
   var RepeatingButton = cr.ui.RepeatingButton;
 
   //
@@ skipping 406 matching lines @@
       if (cr.isChromeOS) {
         $('accessibility-spoken-feedback-check').onchange = function(event) {
           chrome.send('spokenFeedbackChange',
                       [$('accessibility-spoken-feedback-check').checked]);
         };
 
         $('accessibility-high-contrast-check').onchange = function(event) {
           chrome.send('highContrastChange',
                       [$('accessibility-high-contrast-check').checked]);
         };
+        $('accessibility-sticky-keys').hidden =
+            !loadTimeData.getBoolean('enableStickyKeys');
       }
 
       // Display management section (CrOS only).
       if (cr.isChromeOS) {
         $('display-options').onclick = function(event) {
           OptionsPage.navigateToPage('display');
           chrome.send('coreOptionsUserMetricsAction',
                       ['Options_Display']);
         };
       }
@@ skipping 1065 matching lines @@
     BrowserOptions.getLoggedInUsername = function() {
       return BrowserOptions.getInstance().username_;
     };
   }
 
   // Export
   return {
     BrowserOptions: BrowserOptions
   };
 });