Use an enum for ChromeVox queue mode.

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

Index: chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js
diff --git a/chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js b/chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js
index 56a7ec0b842f103e92ff1f812f751c80a12642e2..425762777f72afeb2461ae8bf4715f05e17aadc1 100644
--- a/chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js
+++ b/chrome/browser/resources/chromeos/chromevox/testing/spoken_list_builder.js
@@ -25,7 +25,7 @@ cvox.SpokenListBuilder = function() {
  * @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
 };
 
@@ -36,7 +36,7 @@ cvox.SpokenListBuilder.prototype.flush = function(expectedText) {
  * @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
 };
 
@@ -47,7 +47,7 @@ cvox.SpokenListBuilder.prototype.queue = function(expectedText) {
  * @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
 };