Fix ChromeVox next tests to fail instead of timing out where applicable.

chrome/browser/resources/chromeos/chromevox/testing/chromevox_e2e_test_base.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.
 
 GEN_INCLUDE([
-    'chrome/browser/resources/chromeos/chromevox/testing/common.js']);
+    'chrome/browser/resources/chromeos/chromevox/testing/common.js',
+    'chrome/browser/resources/chromeos/chromevox/testing/callback_helper.js']);
 
 /**
  * Base test fixture for ChromeVox end to end tests.
  *
  * These tests run against production ChromeVox inside of the extension's
  * background page context.
  * @constructor
  */
-function ChromeVoxE2ETest() {}
+function ChromeVoxE2ETest() {
+  this.callbackHelper_ = new CallbackHelper(this);
+}
 
 ChromeVoxE2ETest.prototype = {
   __proto__: testing.Test.prototype,
 
   /**
    * @override
    * No UI in the background context.
    */
   runAccessibilityChecks: false,
 
@@ skipping 68 matching lines @@
     var code = TestUtils.extractHtmlFromCommentEncodedString(function() {/*!
       var target = document.body.querySelector('$1');
       target.focus();
       var evt = document.createEvent('KeyboardEvent');
       evt.initKeyboardEvent('keydown', true, true, window, '$0', 0, false,
           false, false, false);
       document.activeElement.dispatchEvent(evt);
     */}, [key, elementQueryString]);
 
     chrome.tabs.executeScript(tabId, {code: code});
+  },
+
+  /**
+   * Creates a callback that optionally calls {@code opt_callback} when
+   * called.  If this method is called one or more times, then
+   * {@code testDone()} will be called when all callbacks have been called.
+   * @param {Function=} opt_callback Wrapped callback that will have its this
+   *        reference bound to the test fixture.
+   * @return {Function}
+   */
+  newCallback: function(opt_callback) {
+    return this.callbackHelper_.wrap(opt_callback);
   }
 };
 
 /**
  * Similar to |TEST_F|. Generates a test for the given |testFixture|,
  * |testName|, and |testFunction|.
  * Used this variant when an |isAsync| fixture wants to temporarily mix in an
  * sync test.
  * @param {string} testFixture Fixture name.
  * @param {string} testName Test name.
  * @param {function} testFunction The test impl.
  */
 function SYNC_TEST_F(testFixture, testName, testFunction) {
   var wrappedTestFunction = function() {
     testFunction.call(this);
     testDone([true, '']);
   };
   TEST_F(testFixture, testName, wrappedTestFunction);
 }