Fix MediaGalleriesPlatformAppBrowserTest tests with PlzNavigate.

chrome/test/data/extensions/api_test/media_galleries/tourl/test.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.
 
 function check_result_factory(expected) {
   return function() {
     if (expected) {
       chrome.test.succeed();
     } else {
       chrome.test.fail();
     }
   };
 }
 
 function TestImageLoadFactory(url, should_load) {
   return function() {
     test_image = document.createElement('img');
     document.body.appendChild(test_image);
     test_image.addEventListener('load', check_result_factory(should_load));
     test_image.addEventListener('error', check_result_factory(!should_load));
 
     test_image.src = url;
   };
 }
 
-CreateDummyWindowToPreventSleep();
-
 chrome.test.getConfig(function(config) {
   var customArg = JSON.parse(config.customArg);
   var gallery_id = customArg[0];
   var profile_path = customArg[1];
   var extension_url = chrome.runtime.getURL('/');
   var extension_id = extension_url.split('/')[2];
 
   var bad_mount_point = 'filesystem:' + extension_url +
     'external/invalid-' + profile_path + '-' + extension_id + '-' + gallery_id +
     '/test.jpg';
 
   var bad_mount_name = 'filesystem:' + extension_url +
     'external/media_galleries-' + profile_path + '-' + gallery_id + '/test.jpg';
 
   var good_url = 'filesystem:' + extension_url +
     'external/media_galleries-' + profile_path + '-' + extension_id + '-' +
     gallery_id + '/test.jpg';
 
   chrome.test.runTests([
     TestImageLoadFactory(bad_mount_point, false),
     TestImageLoadFactory(bad_mount_name, false),
     TestImageLoadFactory(good_url, true),
   ]);
 })