Fix MediaGalleriesPlatformAppBrowserTest tests with PlzNavigate.

chrome/test/data/extensions/api_test/media_galleries/no_access/test.js

 // Copyright (c) 2012 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.
 
 var mediaGalleries = chrome.mediaGalleries;
 
 var galleries;
 var testResults = [];
 var expectedFileSystems;
 
@@ skipping 20 matching lines @@
 
 var mediaFileSystemsDirectoryErrorCallback = function(err) {
   testResults.push("");
   checkFinished();
 };
 
 var mediaFileSystemsListCallback = function(results) {
   galleries = results;
 };
 
-CreateDummyWindowToPreventSleep();
-
 chrome.test.getConfig(function(config) {
   customArg = JSON.parse(config.customArg);
   expectedFileSystems = customArg[0];
 
   chrome.test.runTests([
     function getMediaFileSystems() {
       mediaGalleries.getMediaFileSystems(
           chrome.test.callbackPass(mediaFileSystemsListCallback));
     },
     function testGalleries() {
       chrome.test.assertEq(expectedFileSystems, galleries.length);
       for (var i = 0; i < galleries.length; i++) {
         var dirReader = galleries[i].root.createReader();
         dirReader.readEntries(mediaFileSystemsDirectoryEntryCallback,
                               mediaFileSystemsDirectoryErrorCallback);
       }
     },
     function validFileCopyToShouldFail() {
       runCopyToTest(validWEBPImageCase, false /* expect failure */);
     },
     function invalidFileCopyToShouldFail() {
       runCopyToTest(invalidWEBPImageCase, false /* expect failure */);
     },
   ]);
 })