Enable a11y audit for chrome://settings

chrome/browser/ui/webui/options/chromeos/accounts_options_browsertest.js

 // Copyright 2013 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.
 
 function AccountsOptionsWebUITest() {}
 
 AccountsOptionsWebUITest.prototype = {
   __proto__: testing.Test.prototype,
 
   /**
    * Browse to accounts options.
    */
   browsePreload: 'chrome://settings-frame/accounts',
+
+  /** @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');
+  },
 };
 
 function createEnterKeyboardEvent(type) {
   return new KeyboardEvent(type, {
     'bubbles': true,
     'cancelable': true,
     'keyIdentifier': 'Enter'
   });
 }
 
 TEST_F('AccountsOptionsWebUITest', 'testNoCloseOnEnter', function() {
   assertEquals(this.browsePreload, document.location.href);
 
   var inputField = $('userNameEdit');
   var accountsOptionsPage = AccountsOptions.getInstance();
 
   // Overlay is visible.
   assertTrue(accountsOptionsPage.visible);
 
   // Simulate pressing the enter key in the edit field.
   inputField.dispatchEvent(createEnterKeyboardEvent('keydown'));
   inputField.dispatchEvent(createEnterKeyboardEvent('keypress'));
   inputField.dispatchEvent(createEnterKeyboardEvent('keyup'));
 
   // Verify the overlay is still visible.
   assertTrue(accountsOptionsPage.visible);
 });