[cros,de-hack] Get rid of singleton for the WebUILoginScreen.

chrome/browser/chromeos/login/base_login_display_host.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_BASE_LOGIN_DISPLAY_HOST_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_BASE_LOGIN_DISPLAY_HOST_H_
 #pragma once
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chromeos/login/login_display.h"
 #include "chrome/browser/chromeos/login/login_display_host.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/gfx/rect.h"
 
 namespace views {
 class Widget;
 }
 
 namespace chromeos {
 
 class ExistingUserController;
-class ViewsOobeDisplay;
 class WizardController;
 
 // An abstract base class that defines OOBE/login screen host.
 // It encapsulates controllers, background integration and flow.
 class BaseLoginDisplayHost : public LoginDisplayHost,
                              public content::NotificationObserver {
  public:
   explicit BaseLoginDisplayHost(const gfx::Rect& background_bounds);
   virtual ~BaseLoginDisplayHost();
 
   // Returns the default LoginDispalyHost instance if it has been created.
   static LoginDisplayHost* default_host() {
     return default_host_;
   }
 
   // LoginDisplayHost implementation:
   virtual void OnSessionStart();
   virtual void StartWizard(
       const std::string& first_screen_name,
       const GURL& start_url);
   virtual void StartSignInScreen();
 
-  // Implementation specific WizardController creation method.
-  virtual WizardController* CreateWizardController();
+  // Creates specific WizardController.
+  virtual WizardController* CreateWizardController() = 0;
 
   const gfx::Rect& background_bounds() const { return background_bounds_; }
 
  private:
   // content::NotificationObserver implementation:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details);
 
   // Used to calculate position of the screens and background.
   gfx::Rect background_bounds_;
 
   content::NotificationRegistrar registrar_;
 
   // Default LoginDisplayHost.
   static LoginDisplayHost* default_host_;
 
   // Sign in screen controller.
   scoped_ptr<ExistingUserController> sign_in_controller_;
 
   // OOBE and some screens (camera, recovery) controller.
   scoped_ptr<WizardController> wizard_controller_;
 
-  // Keeps views based OobeDisplay implementation if any.
-  // TODO(altimofeev): move it to ViewsLoginDisplayHost. Also see comment in
-  // the CreateWizardController().
-  scoped_ptr<ViewsOobeDisplay> oobe_display_;
-
   DISALLOW_COPY_AND_ASSIGN(BaseLoginDisplayHost);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_BASE_LOGIN_DISPLAY_HOST_H_