[Media Router WebUI] Run afterNextRender() before tests using media-router-container.

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

 // Copyright 2016 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 Suite of tests for media-router-container that focus on
  * the MRPM search feature.
  */
 cr.define('media_router_container_search', function() {
   function registerTests() {
     suite('MediaRouterContainerSearch', function() {
@@ skipping 136 matching lines @@
         pseudoSink = new media_router.Sink(
             'pseudo:test', '', null, 'domain.com',
             media_router.SinkIconType.CAST, undefined,
             test_base.castModeBitset);
         pseudoSink.isPseudoSink = true;
         foundSink = new media_router.Sink(
             'found sink id', 'no existing sink', null, pseudoSink.domain,
             pseudoSink.iconType, undefined, pseudoSink.castModes);
         fakeSinkListWithPseudoSink = fakeSinkList.concat([pseudoSink]);
 
-        setTimeout(done);
+        // Allow for the media router container to be created, attached, and
+        // listeners registered in an afterNextRender() call.
+        Polymer.RenderStatus.afterNextRender(this, done);
       });
 
       test('pseudo sink hidden without filter input', function(done) {
         container.allSinks = fakeSinkListWithPseudoSink;
 
         setTimeout(function() {
           var sinkList =
               container.$$('#sink-list').querySelectorAll('paper-item');
           assertEquals(fakeSinkList.length, sinkList.length);
           MockInteractions.tap(container.$['sink-search-icon']);
@@ skipping 292 matching lines @@
             searchState.checkForRealSink(fakeSinkList.concat([foundSink])));
         assertEquals(foundSink.id, searchState.checkForRealSink(fakeSinkList));
       });
     });
   }
 
   return {
     registerTests: registerTests,
   };
 });