--- a/browser/components/sessionstore/test/browser_async_window_flushing.js
+++ b/browser/components/sessionstore/test/browser_async_window_flushing.js
@@ -20,17 +20,17 @@ add_task(async function test_add_interes
   // Make sure we can actually store another closed window
   await pushPrefs(["browser.sessionstore.max_windows_undo",
                    initialClosedWindows + 1]);
 
   // Create a new browser window. Since the default window will start
   // at about:blank, SessionStore should find this tab (and therefore the
   // whole window) uninteresting, and should not initially put it into
   // the closed windows array.
-  let newWin = await BrowserTestUtils.openNewBrowserWindow();
+  let newWin = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
 
   let browser = newWin.gBrowser.selectedBrowser;
 
   // Send a message that will cause the content to change its location
   // to someplace more interesting. We've disabled auto updates from
   // the browser, so the parent won't know about this
   await ContentTask.spawn(browser, PAGE, async function(newPage) {
     content.location = newPage;
@@ -84,17 +84,17 @@ add_task(async function test_remove_unin
   // windows stored. We'll use its length to determine whether or not
   // the window was added or not.
   let initialClosedWindows = ss.getClosedWindowCount();
 
   // Make sure we can actually store another closed window
   await pushPrefs(["browser.sessionstore.max_windows_undo",
                    initialClosedWindows + 1]);
 
-  let newWin = await BrowserTestUtils.openNewBrowserWindow();
+  let newWin = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
 
   // Now browse the initial tab of that window to an interesting
   // site.
   let tab = newWin.gBrowser.selectedTab;
   let browser = tab.linkedBrowser;
   browser.loadURI(PAGE);
 
   await BrowserTestUtils.browserLoaded(browser, false, PAGE);
@@ -146,17 +146,17 @@ add_task(async function test_synchronous
   // windows stored. We'll use its length to determine whether or not
   // the window was added or not.
   let state = JSON.parse(ss.getBrowserState());
   ok(state, "Make sure we can get the state");
   let initialWindows = state.windows.length;
 
   // Open a new window and send the first tab somewhere
   // interesting.
-  let newWin = await BrowserTestUtils.openNewBrowserWindow();
+  let newWin = await BrowserTestUtils.openNewBrowserWindow({}, "about:blank");
   let browser = newWin.gBrowser.selectedBrowser;
   browser.loadURI(PAGE);
   await BrowserTestUtils.browserLoaded(browser, false, PAGE);
   await TabStateFlusher.flush(browser);
 
   state = JSON.parse(ss.getBrowserState());
   is(state.windows.length, initialWindows + 1,
      "The new window to be in the state");

--- a/browser/modules/test/browser/browser_UsageTelemetry.js
+++ b/browser/modules/test/browser/browser_UsageTelemetry.js
@@ -111,17 +111,17 @@ add_task(async function test_tabsAndWind
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:blank"));
   expectedTabOpenCount += 2;
   expectedMaxTabs += 2;
   checkScalars({maxTabs: expectedMaxTabs, tabOpenCount: expectedTabOpenCount, maxWindows: expectedMaxWins,
                 windowsOpenCount: expectedWinOpenCount, totalURIs: 0, domainCount: 0,
                 totalUnfilteredURIs: 0});
 
   // Add a new window and then some tabs in it. An empty new windows counts as a tab.
-  let win = await BrowserTestUtils.openNewBrowserWindow();
+  let win = await BrowserTestUtils.openNewBrowserWindow({}, "");
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(win.gBrowser, "about:blank"));
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(win.gBrowser, "about:blank"));
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:blank"));
   // The new window started with a new tab, so account for it.
   expectedTabOpenCount += 4;
   expectedWinOpenCount += 1;
   expectedMaxWins = 2;
   expectedMaxTabs += 4;
@@ -144,17 +144,17 @@ add_task(async function test_tabsAndWind
                 totalUnfilteredURIs: 0});
 });
 
 add_task(async function test_subsessionSplit() {
   // Let's reset the counts.
   Services.telemetry.clearScalars();
 
   // Add a new window (that will have 4 tabs).
-  let win = await BrowserTestUtils.openNewBrowserWindow();
+  let win = await BrowserTestUtils.openNewBrowserWindow({}, "");
   let openedTabs = [];
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(win.gBrowser, "about:blank"));
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(win.gBrowser, "about:mozilla"));
   openedTabs.push(await BrowserTestUtils.openNewForegroundTab(win.gBrowser, "http://www.example.com"));
 
   // Check that the scalars have the right values. We expect 2 unfiltered URI loads
   // (about:mozilla and www.example.com, but no about:blank) and 1 URI totalURIs
   // (only www.example.com).
@@ -209,17 +209,17 @@ add_task(async function test_URIAndDomai
 
   // Activating a different tab must not increase the URI count.
   let secondTab = await BrowserTestUtils.openNewForegroundTab(gBrowser, "about:blank");
   await BrowserTestUtils.switchTab(gBrowser, firstTab);
   checkCounts({totalURIs: 1, domainCount: 1, totalUnfilteredURIs: 1});
   await BrowserTestUtils.removeTab(secondTab);
 
   // Open a new window and set the tab to a new address.
-  let newWin = await BrowserTestUtils.openNewBrowserWindow();
+  let newWin = await BrowserTestUtils.openNewBrowserWindow({}, "");
   await BrowserTestUtils.loadURI(newWin.gBrowser.selectedBrowser, "http://example.com/");
   await BrowserTestUtils.browserLoaded(newWin.gBrowser.selectedBrowser);
   checkCounts({totalURIs: 2, domainCount: 1, totalUnfilteredURIs: 2});
 
   // We should not count AJAX requests.
   const XHR_URL = "http://example.com/r";
   await ContentTask.spawn(newWin.gBrowser.selectedBrowser, XHR_URL, function(url) {
     return new Promise(resolve => {