Refactor event handler classes to make it easier to add new event type listeners.

chrome/renderer/resources/extensions/automation/automation_node.js

 // Copyright 2014 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.
 
 var AutomationEvent = require('automationEvent').AutomationEvent;
 var automationInternal =
     require('binding').Binding.create('automationInternal').generate();
 var exceptionHandler = require('uncaught_exception_handler');
 var IsInteractPermitted =
     requireNative('automationInternal').IsInteractPermitted;
@@ skipping 613 matching lines @@
     'tableColumnCount',
     'tableColumnIndex',
     'tableRowCount',
     'tableRowIndex',
     'textDirection',
     'textSelEnd',
     'textSelStart',
     'textStyle'];
 
 var nodeRefAttributes = [
-    ['activedescendantId', 'activedescendant'],
+    ['activedescendantId', 'activeDescendant'],
     ['tableColumnHeaderId', 'tableColumnHeader'],
     ['tableHeaderId', 'tableHeader'],
     ['tableRowHeaderId', 'tableRowHeader'],
     ['titleUiElement', 'titleUIElement']];
 
 var intListAttributes = [
     'characterOffsets',
     'lineBreaks',
     'wordEnds',
     'wordStarts'];
@@ skipping 363 matching lines @@
 utils.defineProperty(AutomationRootNode, 'getOrCreate', function(treeID) {
   return AutomationRootNodeImpl.getOrCreate(treeID);
 });
 
 utils.defineProperty(AutomationRootNode, 'destroy', function(treeID) {
   AutomationRootNodeImpl.destroy(treeID);
 });
 
 exports.$set('AutomationNode', AutomationNode);
 exports.$set('AutomationRootNode', AutomationRootNode);