Add unit test for lock and unlock virtual keyboard feature

ui/keyboard/resources/elements/kb-shift-key.html

 <!--
   -- 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.
   -->
 
 <polymer-element name="kb-shift-key"
     attributes="lowerCaseKeysetId upperCaseKeysetId"
     class="shift dark" char="Shift" on-pointerout="{{out}}" extends="kb-key">
   <script>
@@ skipping 111 matching lines @@
           // Populate double click transition details.
           var detail = {};
           detail.char = this.char || this.textContent;
           detail.toKeyset = this.upperCaseKeysetId;
           detail.nextKeyset = undefined;
           detail.callback = this.onDoubleClick;
           this.fire('enable-dbl', detail);
         },
 
         generateLongPressTimer: function() {
-          return this.asyncMethod(function() {
+          return this.async(function() {
             var detail = this.populateDetails();
             if (state == KEY_STATES.LOCKED) {
               // We don't care about the longpress if we are already
               // capitalized.
               return;
             } else {
               state = KEY_STATES.LOCKED;
               detail.toKeyset = this.upperCaseKeysetId;
               detail.nextKeyset = undefined;
             }
@@ skipping 102 matching lines @@
             case KEY_STATES.UNLOCKED:
               return this.lowerCaseKeysetId;
             default:
               return this.upperCaseKeysetId;
           }
         },
       });
     })();
   </script>
 </polymer-element>