Move all typecasting code to individual screens.

chrome/browser/chromeos/login/wizard_controller_browsertest.cc

 // 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.
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/path_service.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
@@ skipping 722 matching lines @@
   OnExit(ScreenObserver::EULA_ACCEPTED);
   // Let update screen smooth time process (time = 0ms).
   content::RunAllPendingInMessageLoop();
 
   CheckCurrentScreen(WizardController::kUpdateScreenName);
   EXPECT_CALL(*mock_update_screen_, Hide()).Times(1);
   EXPECT_CALL(*mock_auto_enrollment_check_screen_, Show()).Times(1);
   OnExit(ScreenObserver::UPDATE_INSTALLED);
 
   AutoEnrollmentCheckScreen* screen =
-      WizardController::default_controller()->GetAutoEnrollmentCheckScreen();
+      AutoEnrollmentCheckScreen::Get(WizardController::default_controller());
   EXPECT_EQ(screen,
             WizardController::default_controller()->current_screen());
   EXPECT_CALL(*mock_auto_enrollment_check_screen_, Hide()).Times(1);
   screen->Start();
   // Wait for auto-enrollment controller to encounter the connection error.
   WaitForAutoEnrollmentState(policy::AUTO_ENROLLMENT_STATE_CONNECTION_ERROR);
 
   // The error screen shows up if there's no auto-enrollment decision.
   EXPECT_FALSE(StartupUtils::IsOobeCompleted());
   EXPECT_EQ(GetErrorScreen(),
@@ skipping 312 matching lines @@
 // TODO(merkulova): Add tests for bluetooth HID detection screen variations when
 // UI and logic is ready. http://crbug.com/127016
 
 // TODO(dzhioev): Add tests for controller/host pairing flow.
 // http://crbug.com/375191
 
 COMPILE_ASSERT(ScreenObserver::EXIT_CODES_COUNT == 23,
                add_tests_for_new_control_flow_you_just_introduced);
 
 }  // namespace chromeos