Fix MediaGalleriesPlatformAppBrowserTest tests with PlzNavigate.

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

Index: chrome/test/data/extensions/api_test/media_galleries/tourl/test.js
diff --git a/chrome/test/data/extensions/api_test/media_galleries/tourl/test.js b/chrome/test/data/extensions/api_test/media_galleries/tourl/test.js
index 43baf0f8fd3798b2d37d74035af8f8c8ee16a0ae..cb76b4919353629781e58cc73f582bcd6c4abbb6 100644
--- a/chrome/test/data/extensions/api_test/media_galleries/tourl/test.js
+++ b/chrome/test/data/extensions/api_test/media_galleries/tourl/test.js
@@ -23,8 +23,6 @@ function TestImageLoadFactory(url, should_load) {
   };
 }
 
-CreateDummyWindowToPreventSleep();
-
 chrome.test.getConfig(function(config) {
   var customArg = JSON.parse(config.customArg);
   var gallery_id = customArg[0];