[Media Router WebUI] Handle on dialog load focus on Mac.

chrome/test/data/webui/media_router/media_router_elements_browsertest.js

 // Copyright 2015 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 Runs the Media Router Polymer elements tests. */
 
 /** @const {string} Path to source root. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 21 matching lines @@
   // split between media_router_container_tests.js and
   // media_router_container_filter_tests.js.
   extraLibraries: PolymerTest.getLibraries(ROOT_PATH).concat([
     'issue_banner_tests.js',
     'media_router_container_tests.js',
     'media_router_container_filter_tests.js',
     'media_router_header_tests.js',
     'media_router_search_highlighter.js',
     'route_details_tests.js',
   ]),
+
+  /** @override */
+  setUp: function() {
+    PolymerTest.prototype.setUp.call(this);
+
+    // This element is used as a focus placeholder on dialog open, then
+    // deleted. The user will be unable to tab to it. Remove when there is a
+    // long term fix.
+    this.accessibilityAuditConfig.ignoreSelectors(
+       'focusableElementNotVisibleAndNotAriaHidden', '#focus-placeholder');
+  },
 };
 
 TEST_F('MediaRouterElementsBrowserTest', 'MediaRouterElementsTestIssueBanner',
     function() {
   // Register mocha tests for the issue banner.
   issue_banner.registerTests();
 
   // Run all registered tests.
   mocha.run();
 });
@@ skipping 40 matching lines @@
 
 TEST_F('MediaRouterElementsBrowserTest',
     'MediaRouterElementsTestMediaRouterRouteDetails',
     function() {
   // Register mocha tests for the route details.
   route_details.registerTests();
 
   // Run all registered tests.
   mocha.run();
 });