Add unit test for lock and unlock virtual keyboard feature

chrome/test/data/chromeos/virtual_keyboard/control_keys_test.js

 /*
  * Copyright 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.
  */
 
 /**
  * Class for testing keyset transitions resulting from use of the left or right
  * shift key. Keyset transitions are asynchronous, and each test needs to be
  * broken into subtasks in order to synchronize with keyset updates.
@@ skipping 301 matching lines @@
  * Tests that pressing the hide keyboard key calls the appropriate hide keyboard
  * API. The test is run asynchronously since the keyboard loads keysets
  * dynamically.
  */
 function testHideKeyboard(testDoneCallback) {
   var runTest = function() {
     var hideKey = $('keyboard').querySelector('kb-hide-keyboard-key');
     assertTrue(!!hideKey, 'Unable to find key');
 
     chrome.virtualKeyboardPrivate.hideKeyboard.addExpectation();
+    chrome.virtualKeyboardPrivate.lockKeyboard.addExpectation(false);
 
     hideKey.down();
     hideKey.up();
   };
   onKeyboardReady('testHideKeyboard', runTest, testDoneCallback);
 }