Use an enum for ChromeVox queue mode.

chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js

 // 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.
 
 /**
  * @fileoverview The spoken list builder. Used in test cases.
  */
 
 goog.provide('cvox.SpokenListBuilder');
-
+goog.require('cvox.QueueMode');
 
 
 /**
  * Builds a spoken list.
  * @constructor
  */
 cvox.SpokenListBuilder = function() {
   this.list_ = [];
 };
 
 
 /**
  * Adds an expected flushed utterance to the builder.
  * @param {string} expectedText The expected text.
  * @return {cvox.SpokenListBuilder} this.
  */
 cvox.SpokenListBuilder.prototype.flush = function(expectedText) {
-  this.list_.push([expectedText, cvox.AbstractTts.QUEUE_MODE_FLUSH]);
+  this.list_.push([expectedText, cvox.QueueMode.FLUSH]);
   return this;  // for chaining
 };
 
 
 /**
  * Adds an expected queued utterance to the builder.
  * @param {string} expectedText The expected text.
  * @return {cvox.SpokenListBuilder} this.
  */
 cvox.SpokenListBuilder.prototype.queue = function(expectedText) {
-  this.list_.push([expectedText, cvox.AbstractTts.QUEUE_MODE_QUEUE]);
+  this.list_.push([expectedText, cvox.QueueMode.QUEUE]);
   return this;  // for chaining
 };
 
 
 /**
  * Adds an expected category-flush utterance to the builder.
  * @param {string} expectedText The expected text.
  * @return {cvox.SpokenListBuilder} this.
  */
 cvox.SpokenListBuilder.prototype.categoryFlush = function(expectedText) {
-  this.list_.push([expectedText, cvox.AbstractTts.QUEUE_MODE_CATEGORY_FLUSH]);
+  this.list_.push([expectedText, cvox.QueueMode.CATEGORY_FLUSH]);
   return this;  // for chaining
 };
 
 
 /**
  * Builds the list.
  * @return {Array} The array of utterances.
  */
 cvox.SpokenListBuilder.prototype.build = function() {
   return this.list_;
 };