diff --git a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_cookieacceptdialog.js b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_cookieacceptdialog.js
index a21aa7c3151d..98876ac54c6a 100644
--- a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_cookieacceptdialog.js
+++ b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_cookieacceptdialog.js
@@ -5,7 +5,7 @@
 // This test makes sure that private browsing mode disables the "remember"
 // option in the cookie accept dialog.
 
-function test() {
+add_task(function* test() {
   // initialization
   const TEST_URL = "http://mochi.test:8888/browser/browser/components/" +
                    "privatebrowsing/test/browser/" +
@@ -14,36 +14,8 @@ function test() {
   let cp = Cc["@mozilla.org/embedcomp/cookieprompt-service;1"].
            getService(Ci.nsICookiePromptService);
 
-  waitForExplicitFinish();
-
-  function checkRememberOption(expectedDisabled, aWindow, callback) {
-    function observer(aSubject, aTopic, aData) {
-      if (aTopic != "domwindowopened")
-        return;
-
-      Services.ww.unregisterNotification(observer);
-      let win = aSubject.QueryInterface(Ci.nsIDOMWindow);
-      win.addEventListener("load", function onLoad(event) {
-        win.removeEventListener("load", onLoad, false);
-
-        executeSoon(function () {
-          let doc = win.document;
-          let remember = doc.getElementById("persistDomainAcceptance");
-          ok(remember, "The remember checkbox should exist");
-
-          if (expectedDisabled)
-            is(remember.getAttribute("disabled"), "true",
-               "The checkbox should be disabled");
-          else
-            ok(!remember.hasAttribute("disabled"),
-               "The checkbox should not be disabled");
-
-          waitForWindowClose(win, callback);
-        });
-      }, false);
-    }
-    Services.ww.registerNotification(observer);
 
+  function openCookieDialog(aWindow) {
     let remember = {};
     const time = (new Date("Jan 1, 2030")).getTime() / 1000;
     let cookie = {
@@ -67,95 +39,90 @@ function test() {
         throw Cr.NS_ERROR_NO_INTERFACE;
       }
     };
-    cp.cookieDialog(aWindow, cookie, "mozilla.org", 10, false, remember);
-  }
 
-  function checkSettingDialog(aIsPrivateWindow, aWindow, aCallback) {
-    let selectedBrowser = aWindow.gBrowser.selectedBrowser;
+    executeSoon(function () {
+      cp.cookieDialog(aWindow, cookie, "mozilla.org", 10, false, remember);
+    });
+    return BrowserTestUtils.domWindowOpened();
+  };
 
-    function onLoad() {
-      if (aWindow.content.location.href != TEST_URL) {
-        selectedBrowser.loadURI(TEST_URL);
-        return;
-      }
-      selectedBrowser.removeEventListener("load", onLoad, true);
-      Services.ww.unregisterNotification(observer);
 
-      ok(aIsPrivateWindow,
-         "Confirm setting dialog is not displayed for private window");
+  function checkRememberOption(expectedDisabled, aWindow) {
+    return Task.spawn(function* () {
+      let dialogWin = yield openCookieDialog(aWindow);
 
-      executeSoon(aCallback);
-    }
-    selectedBrowser.addEventListener("load", onLoad, true);
-
-    function observer(aSubject, aTopic, aData) {
-      if (aTopic != "domwindowopened")
-        return;
-      selectedBrowser.removeEventListener("load", onLoad, true);
-      Services.ww.unregisterNotification(observer);
-      ok(!aIsPrivateWindow,
-         "Confirm setting dialog is displayed for normal window");
-      let win = aSubject.QueryInterface(Ci.nsIDOMWindow);
-      executeSoon(function () {
-        info("Wait for window close");
-        waitForWindowClose(win, aCallback);
+      yield new Promise(resolve => {
+        dialogWin.addEventListener("load", function onLoad(event) {
+          dialogWin.removeEventListener("load", onLoad, false);
+          resolve();
+        }, false);
       });
-    }
-    Services.ww.registerNotification(observer);
 
-    selectedBrowser.loadURI(TEST_URL);
-  }
+      let doc = dialogWin.document;
+      let remember = doc.getElementById("persistDomainAcceptance");
+      ok(remember, "The remember checkbox should exist");
 
-  let windowsToClose = [];
-  function testOnWindow(aIsPrivate, aCallback) {
-    whenNewWindowLoaded({private: aIsPrivate}, function(aWin) {
-      windowsToClose.push(aWin);
-      let selectedBrowser = aWin.gBrowser.selectedBrowser;
-      selectedBrowser.addEventListener("load", function onLoad() {
-        if (aWin.content.location.href != BLANK_URL) {
-          selectedBrowser.loadURI(BLANK_URL);
-          return;
-        }
-        selectedBrowser.removeEventListener("load", onLoad, true);
-        executeSoon(function() aCallback(aWin));
-      }, true);
-      selectedBrowser.loadURI(BLANK_URL);
+      if (expectedDisabled)
+        is(remember.getAttribute("disabled"), "true",
+           "The checkbox should be disabled");
+      else
+        ok(!remember.hasAttribute("disabled"),
+           "The checkbox should not be disabled");
+
+      yield BrowserTestUtils.closeWindow(dialogWin);
     });
-  }
+  };
 
-  registerCleanupFunction(function() {
-    Services.prefs.clearUserPref("network.cookie.lifetimePolicy");
-    windowsToClose.forEach(function(aWin) {
-      aWin.close();
+  function checkSettingDialog(aIsPrivateWindow, aWindow) {
+    return Task.spawn(function* () {
+      let dialogOpened = false;
+      let promiseDialogClosed = null;
+
+      function observer(subject, topic, data) {
+        if (topic != "domwindowopened") { return; }
+        Services.ww.unregisterNotification(observer);
+        dialogOpened = true;
+
+        promiseDialogClosed = BrowserTestUtils.closeWindow(
+          subject.QueryInterface(Ci.nsIDOMWindow));
+      }
+      Services.ww.registerNotification(observer);
+
+      let selectedBrowser = aWindow.gBrowser.selectedBrowser;
+      selectedBrowser.loadURI(TEST_URL);
+      yield BrowserTestUtils.browserLoaded(selectedBrowser);;
+
+      if (dialogOpened) {
+        ok(!aIsPrivateWindow,
+           "Setting dialog shown, confirm normal window");
+      } else {
+        Services.ww.unregisterNotification(observer);
+        ok(aIsPrivateWindow,
+           "Confirm setting dialog is not displayed for private window");
+      }
+
+      yield promiseDialogClosed;
     });
-  });
+  };
 
   // Ask all cookies
   Services.prefs.setIntPref("network.cookie.lifetimePolicy", 1);
 
-  testOnWindow(false, function(aWin) {
-    info("Test on public window");
-    checkRememberOption(false, aWin, function() {
-      checkSettingDialog(false, aWin, function() {
-        testOnWindow(true, function(aPrivWin) {
-          info("Test on private window");
-          checkRememberOption(true, aPrivWin, function() {
-            checkSettingDialog(true, aPrivWin, finish);
-          });
-        });
-      });
-    });
-  });
-}
+  let win = yield BrowserTestUtils.openNewBrowserWindow();
+  info("Test on public window");
 
-function waitForWindowClose(aWin, aCallback) {
-  function observer(aSubject, aTopic, aData) {
-    if (aTopic == "domwindowclosed") {
-      info("Window closed");
-      Services.ww.unregisterNotification(observer);
-      executeSoon(aCallback);
-    }
-  }
-  Services.ww.registerNotification(observer);
-  aWin.close();
-}
+  yield checkRememberOption(false, win);
+  yield checkSettingDialog(false, win);
+
+  let privateWin = yield BrowserTestUtils.openNewBrowserWindow({private: true});
+  info("Test on private window");
+
+  yield checkRememberOption(true, privateWin);
+  yield checkSettingDialog(true, privateWin);
+
+
+  // Cleanup
+  Services.prefs.clearUserPref("network.cookie.lifetimePolicy");
+  yield BrowserTestUtils.closeWindow(win);
+  yield BrowserTestUtils.closeWindow(privateWin);
+});
diff --git a/testing/mochitest/BrowserTestUtils/BrowserTestUtils.jsm b/testing/mochitest/BrowserTestUtils/BrowserTestUtils.jsm
index 3482c70e0f2d..b9324eec47ec 100644
--- a/testing/mochitest/BrowserTestUtils/BrowserTestUtils.jsm
+++ b/testing/mochitest/BrowserTestUtils/BrowserTestUtils.jsm
@@ -59,6 +59,23 @@ this.BrowserTestUtils = {
     });
   },
 
+  /**
+   * @return {Promise}
+   *         A Promise which resolves when a "domwindowopened" notification
+   *         has been fired by the window watcher.
+   */
+  domWindowOpened() {
+    return new Promise(resolve => {
+      function observer(subject, topic, data) {
+        if (topic != "domwindowopened") { return; }
+
+        Services.ww.unregisterNotification(observer);
+        resolve(subject.QueryInterface(Ci.nsIDOMWindow));
+      }
+      Services.ww.registerNotification(observer);
+    });
+  },
+
   /**
    * @param {Object} options
    *        {
@@ -89,6 +106,29 @@ this.BrowserTestUtils = {
                                    subject => subject == win).then(() => win);
   },
 
+  /**
+   * Closes a window.
+   *
+   * @param {Window}
+   *        A window to close.
+   *
+   * @return {Promise}
+   *         Resolves when the provided window has been closed.
+   */
+  closeWindow(win) {
+    return new Promise(resolve => {
+      function observer(subject, topic, data) {
+        if (topic == "domwindowclosed" && subject === win) {
+          Services.ww.unregisterNotification(observer);
+          resolve();
+        }
+      }
+      Services.ww.registerNotification(observer);
+      win.close();
+    });
+  },
+
+
   /**
    * Waits a specified number of miliseconds for a specified event to be
    * fired on a specified element.