Add the listbox earcon back to the popupbutton output rule.

chrome/browser/resources/chromeos/chromevox/cvox2/background/output.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 Provides output services for ChromeVox.
  */
 
 goog.provide('Output');
 goog.provide('Output.EventType');
@@ skipping 113 matching lines @@
   menuItem: {
     msgId: 'aria_role_menuitem'
   },
   menuListOption: {
     msgId: 'aria_role_menuitem'
   },
   menuListPopup: {
     msgId: 'aria_role_menu'
   },
   popUpButton: {
-    msgId: 'tag_button'
+    msgId: 'tag_button',
+    earcon: 'LISTBOX'
   },
   radioButton: {
     msgId: 'input_type_radio'
   },
   spinButton: {
     msgId: 'aria_role_combobox',
     earcon: 'LISTBOX'
   },
   textBox: {
     msgId: 'input_type_text',
@@ skipping 840 matching lines @@
     }
 
     if (currentNode != root)
       throw 'Unbalanced parenthesis.';
 
     return root;
   }
 };
 
 });  // goog.scope