--- a/browser/components/extensions/test/browser/browser_ext_sessions_restore.js
+++ b/browser/components/extensions/test/browser/browser_ext_sessions_restore.js
@@ -60,17 +60,17 @@ add_task(async function test_sessions_re
   function checkLocalTab(tab, expectedUrl) {
     let realTab = tabTracker.getTab(tab.id);
     let tabState = JSON.parse(SessionStore.getTabState(realTab));
     is(tabState.entries[0].url, expectedUrl, "restored tab has the expected url");
   }
 
   await extension.awaitMessage("ready");
 
-  let win = await BrowserTestUtils.openNewBrowserWindow();
+  let win = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
   await BrowserTestUtils.loadURI(win.gBrowser.selectedBrowser, "about:config");
   await BrowserTestUtils.browserLoaded(win.gBrowser.selectedBrowser);
   for (let url of ["about:robots", "about:mozilla"]) {
     await BrowserTestUtils.openNewForegroundTab(win.gBrowser, url);
   }
   await BrowserTestUtils.closeWindow(win);
   await assertNotificationCount(1);
 

--- a/browser/components/extensions/test/browser/browser_ext_tabs_move_window.js
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_move_window.js
@@ -1,15 +1,15 @@
 /* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim: set sts=2 sw=2 et tw=80: */
 "use strict";
 
 add_task(async function() {
   await BrowserTestUtils.openNewForegroundTab(gBrowser, "http://example.net/");
-  let window1 = await BrowserTestUtils.openNewBrowserWindow();
+  let window1 = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
   await BrowserTestUtils.openNewForegroundTab(window1.gBrowser, "http://example.com/");
 
   let extension = ExtensionTestUtils.loadExtension({
     manifest: {
       "permissions": ["tabs"],
     },
 
     async background() {

--- a/browser/components/extensions/test/browser/browser_ext_tabs_update_url.js
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_update_url.js
@@ -129,17 +129,17 @@ add_task(async function test_update_relo
       });
 
       browser.history.onVisited.addListener(data => {
         browser.test.sendMessage("historyAdded");
       });
     },
   });
 
-  let win = await BrowserTestUtils.openNewBrowserWindow();
+  let win = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
   let tabBrowser = win.gBrowser.selectedBrowser;
   await BrowserTestUtils.loadURI(tabBrowser, URL);
   await BrowserTestUtils.browserLoaded(tabBrowser, false, URL);
   let tab = win.gBrowser.selectedTab;
 
   async function getTabHistory() {
     await TabStateFlusher.flush(tabBrowser);
     return JSON.parse(SessionStore.getTabState(tab));