Use an enum for ChromeVox queue mode.

chrome/browser/resources/chromeos/chromevox/host/interface/abstract_tts.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.
 
 /**
  * @fileoverview Base class for Text-to-Speech engines that actually transform
  * text to speech.
  *
  */
 
@@ skipping 402 matching lines @@
 
 
 /**
  * Flag indicating if the TTS is being debugged.
  * @type {boolean}
  */
 cvox.AbstractTts.DEBUG = true;
 
 
 /**
- * Speech queue mode that interrupts the current utterance.
- * @type {number}
- */
-cvox.AbstractTts.QUEUE_MODE_FLUSH = 0;
-
-
-/**
- * Speech queue mode that does not interrupt the current utterance.
- * @type {number}
- */
-cvox.AbstractTts.QUEUE_MODE_QUEUE = 1;
-
-
-/**
- * Speech queue mode that flushes all utterances of the same category
- * (as set by properties['category']).
- * @type {number}
- */
-cvox.AbstractTts.QUEUE_MODE_CATEGORY_FLUSH = 2;
-
-
-/**
  * Character dictionary. These symbols are replaced with their human readable
  * equivalents. This replacement only occurs for single character utterances.
  * @type {Object.<string, string>}
  */
 cvox.AbstractTts.CHARACTER_DICTIONARY = {
   ' ': 'space',
   '`': 'backtick',
   '~': 'tilde',
   '!': 'exclamation',
   '@': 'at',
@@ skipping 152 matching lines @@
           .format({'COUNT': count}) + ' ';
 };
 
 
 /**
  * @override
  */
 cvox.AbstractTts.prototype.getDefaultProperty = function(property) {
   return this.propertyDefault[property];
 };