cros: Various fixes needed for preloading lock screen.

chrome/browser/chromeos/login/ui/user_adding_screen_browsertest.cc

 // Copyright 2014 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.
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm_shell.h"
 #include "base/macros.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker_tester.h"
@@ skipping 248 matching lines @@
 IN_PROC_BROWSER_TEST_F(UserAddingScreenTest, ScreenVisibility) {
   LoginUser(kTestUsers[0]);
 
   UserAddingScreen::Get()->Start();
   content::RunAllPendingInMessageLoop();
   CheckScreenIsVisible();
   UserAddingScreen::Get()->Cancel();
   WaitUntilUserAddingFinishedOrCancelled();
   content::RunAllPendingInMessageLoop();
 
-  ScreenLocker::Show();
-  content::WindowedNotificationObserver(
-      chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
-      content::NotificationService::AllSources()).Wait();
+  {
+    content::WindowedNotificationObserver observer(
+        chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
+        content::NotificationService::AllSources());
+    ScreenLocker::Show();
+    observer.Wait();
+  }
 
-  ScreenLocker::Hide();
-  content::WindowedNotificationObserver(
-      chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
-      content::NotificationService::AllSources()).Wait();
+  {
+    content::WindowedNotificationObserver observer(
+        chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
+        content::NotificationService::AllSources());
+    ScreenLocker::Hide();
+    observer.Wait();
+  }
 
   UserAddingScreen::Get()->Start();
   content::RunAllPendingInMessageLoop();
   CheckScreenIsVisible();
   UserAddingScreen::Get()->Cancel();
   WaitUntilUserAddingFinishedOrCancelled();
   content::RunAllPendingInMessageLoop();
 }
 
 }  // namespace chromeos