Enable a11y audit for chrome://settings

chrome/browser/ui/webui/options/language_options_browsertest.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.
 
 /**
  * TestFixture for language options WebUI testing.
  * @extends {testing.Test}
  * @constructor
  */
 function LanguageOptionsWebUITest() {}
 
 LanguageOptionsWebUITest.prototype = {
   __proto__: testing.Test.prototype,
 
   /** @override */
   browsePreload: 'chrome://settings-frame/languages',
+
+  /** @override */
+  runAccessibilityChecks: true,
+
+  /** @override */
+  accessibilityIssuesAreErrors: true,
+
+  /** override */
+  setUp: function() {
+    // user-image-stream is a streaming video element used for capturing a
+    // user image.
+    this.accessibilityAuditConfig.ignoreSelectors('videoWithoutCaptions',
+                                                  '.user-image-stream');
+  },
 };
 
 // Test opening language options has correct location.
 TEST_F('LanguageOptionsWebUITest', 'testOpenLanguageOptions', function() {
   assertEquals(this.browsePreload, document.location.href);
 });
 
 GEN('#if defined(OS_WIN) || defined(OS_CHROMEOS)');
 // Test reselecting the same language as the current UI locale. This should show
 // a "Chrome is displayed in this language" message rather than a restart banner
 // or a [ Display Chrome in this language ] button.
 TEST_F('LanguageOptionsWebUITest', 'reselectUILocale', function() {
   var currentLang = loadTimeData.getString('currentUiLanguageCode');
   $('language-options-list').selectLanguageByCode(currentLang);
   LanguageOptions.uiLanguageSaved(currentLang);
 
   expectTrue($('language-options-ui-language-button').hidden);
   expectFalse($('language-options-ui-language-message').hidden);
   expectTrue($('language-options-ui-notification-bar').hidden);
 });
 GEN('#endif');  // defined(OS_WIN) || defined(OS_CHROMEOS)