Add unit test for lock and unlock virtual keyboard feature

ui/keyboard/resources/elements/kb-key-base.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-key-base"
     on-pointerdown="{{down}}" on-pointerup="{{up}}" on-pointerout="{{out}}"
     attributes="char invert repeat hintText toKeyset toLayout">
   <script>
@@ skipping 201 matching lines @@
               detail.nextKeyset = this.keysetRules.down[NEXT_KEYSET - OFFSET];
             }
             break;
           default:
             break;
         }
         return detail;
       },
 
       generateLongPressTimer: function() {
-        return this.asyncMethod(function() {
+        return this.async(function() {
           var detail = {
             char: this.charValue,
             hintText: this.hintTextValue
           };
           if (this.keysetRules && this.keysetRules.long != undefined) {
             detail.toKeyset = this.keysetRules.long[TO_KEYSET - OFFSET];
             detail.nextKeyset = this.keysetRules.long[NEXT_KEYSET - OFFSET];
           }
           this.fire('key-longpress', detail);
         }, null, LONGPRESS_DELAY_MSEC);
       },
     });
   </script>
 </polymer-element>