Move all typecasting code to individual screens.

chrome/browser/chromeos/login/screen_manager.h

Index: chrome/browser/chromeos/login/screen_manager.h
diff --git a/chrome/browser/chromeos/login/screen_manager.h b/chrome/browser/chromeos/login/screen_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..1cd1ff14a4e6424350fde9117430349b74d53d84
--- /dev/null
+++ b/chrome/browser/chromeos/login/screen_manager.h
@@ -0,0 +1,48 @@
+// Copyright (c) 2012 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_SCREEN_MANAGER_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_SCREEN_MANAGER_H_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/linked_ptr.h"
+#include "chrome/browser/chromeos/login/screens/wizard_screen.h"
+
+namespace chromeos {
+
+// Class that manages creation and ownership of screens.
+class ScreenManager {
+ public:
+  ScreenManager();
+  virtual ~ScreenManager();
+
+  // Getter for screen with lazy initialization.
+  WizardScreen* GetScreen(const std::string& screen_name);
+
+  // Factory for screen instances.
+  virtual WizardScreen* CreateScreen(const std::string& screen_name) = 0;
+
+  bool HasScreen(const std::string& screen_name);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(EnrollmentScreenTest, TestCancel);
+  FRIEND_TEST_ALL_PREFIXES(WizardControllerFlowTest, Accelerators);
+  friend class WizardControllerFlowTest;
+  friend class WizardControllerOobeResumeTest;
+  friend class WizardInProcessBrowserTest;
+  friend class WizardControllerBrokenLocalStateTest;
+
+  // Screens.
+  typedef std::map<std::string, linked_ptr<WizardScreen> > ScreenMap;
+  ScreenMap screens_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScreenManager);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREEN_MANAGER_H_