Refactor: Extract a KeyboardHandler and CommandHandler from Background

chrome/browser/resources/chromeos/chromevox/cvox2/background/live_regions_test.extjs

 // Copyright 2015 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.
 
 // Include test fixture.
 GEN_INCLUDE(['../../testing/chromevox_next_e2e_test_base.js',
              '../../testing/assert_additions.js']);
 
 GEN_INCLUDE(['../../testing/mock_feedback.js']);
 
@@ skipping 25 matching lines @@
     return mockFeedback;
   },
 
   /**
    * Create a function which performs the command |cmd|.
    * @param {string} cmd
    * @return {function() : void}
    */
   doCmd: function(cmd) {
     return function() {
-      ChromeVoxState.instance.onGotCommand(cmd);
+      CommandHandler.onCommand(cmd);
     };
   },
 };
 
 TEST_F('LiveRegionsTest', 'LiveRegionAddElement', function() {
   var mockFeedback = this.createMockFeedback();
   this.runWithLoadedTree(
     function() {/*!
       <h1>Document with live region</h1>
       <p id="live" aria-live="polite"></p>
@@ skipping 186 matching lines @@
     var focusAfterNodeChange = window.setTimeout.bind(window, function() {
       root.firstChild.nextSibling.focus();
     }, 1000);
     mockFeedback.call(focusAfterNodeChange)
         .expectSpeech('hello!')
         .expectNextSpeechUtteranceIsNot('hello!')
         .expectNextSpeechUtteranceIsNot('hello!')       ;
     mockFeedback.replay();
   });
 });