Make earcon ids strings instead of numbers.

chrome/browser/resources/chromeos/chromevox/walkers/layout_line_walker_test.unitjs

 // 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.
 
 // Include test fixture.
 GEN_INCLUDE(['../testing/chromevox_unittest_base.js']);
 
 /**
  * Test fixture.
  * @constructor
@@ skipping 45 matching lines @@
   
     this.line3Text =
         'Braille also benefits greatly from this type of formatting since ' +
         'some displays can handle lots of text like 80 cell displays!';
   
     this.line1Description =
         [{'context': '', 'text': 'Demonstrating that in-line links like',
           'userValue': '', 'annotation': '', 'earcons': [], 'personality': null,
           'hint': '', 'category': null},
          {'context': '', 'text': 'google', 'userValue': '', 'annotation': 'Link',
-          'earcons': [cvox.AbstractEarcons.LINK], 'personality': null,
+          'earcons': [cvox.Earcon.LINK], 'personality': null,
           hint: '', 'category': null},
          {'context': '', 'text': 'are considered a single layout line.',
           'userValue': '', 'annotation': '', 'earcons': [], 'personality': null,
           'hint': '', 'category': null}];
   
     this.line2Description =
         [{'context': '', 'text':
           'This includes a paragraph that has a lot of text like this one.',
           'userValue': '', 'annotation': '', 'earcons': [], 'personality': null,
           'hint': '', 'category': null},
          {'context': '',
           'text': 'Wikipedia',
           'userValue': '',
           'annotation': 'Link',
-          'earcons': [cvox.AbstractEarcons.LINK],
+          'earcons': [cvox.Earcon.LINK],
           'personality': null,
           'hint': '', 'category': null},
          {'context': '', 'text':
           'is a great example of a site that this walker becomes valuable.',
           'userValue': '',  
           'annotation': '', 'earcons': [], 'personality': null,
           'hint': '', 'category': null}];
   }
 };
 
@@ skipping 78 matching lines @@
 
   // First line.
   sel = this.walker.next(sel);
   assertEquals(this.line1Text, sel.getText());
 
   // Wrap.
   sel.setReversed(true);
   sel = this.walker.next(sel);
   assertEquals(null, sel);
 });