Creating options page and storing preferences.

chrome/browser/resources/chromeos/switch_access/switch_access_unittest.gtestjs

 // Copyright 2017 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.
 
 /**
  * Test fixture for switch_access.js.
  * @constructor
  * @extends {testing.Test}
  */
 function SwitchAccessUnitTest () {
   testing.Test.call(this);
 };
 
 SwitchAccessUnitTest.prototype = {
   __proto__: testing.Test.prototype,
 
   /** @override */
   extraLibraries: [
     'test_support.js',
+    'prefs.js',
     'switch_access.js',
     'testable_switch_access.js',
   ],
 
   getSampleTree: function() {
     // root
     //   middle1
     //     leaf1
     //     leaf2
     //     leaf3
@@ skipping 96 matching lines @@
   let node2 = {state: {}};
   let node3 = {state: {focusable: false}};
   let node4 = {state: {focusable: true}};
   let tsa = new TestableSwitchAccess();
 
   assertTrue(tsa.isInteresting(node1) === undefined);
   assertTrue(tsa.isInteresting(node2) === undefined);
   assertFalse(tsa.isInteresting(node3));
   assertTrue(tsa.isInteresting(node4));
 });