cros: Break BaseScreenHandler into two classes.

chrome/browser/chromeos/login/enrollment/enrollment_screen_view.h

 // 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_ENROLLMENT_ENROLLMENT_SCREEN_VIEW_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_ENROLLMENT_ENROLLMENT_SCREEN_VIEW_H_
 
 #include <string>
 
 #include "chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper.h"
+#include "chrome/browser/chromeos/login/oobe_screen.h"
 
 class GoogleServiceAuthError;
 
 namespace policy {
 struct EnrollmentConfig;
 class EnrollmentStatus;
 }
 
 namespace chromeos {
 
 // Interface class for the enterprise enrollment screen view.
 class EnrollmentScreenView {
  public:
   // This defines the interface for controllers which will be called back when
   // something happens on the UI.
   class Controller {
    public:
     virtual ~Controller() {}
 
     virtual void OnLoginDone(const std::string& user,
                              const std::string& auth_code) = 0;
     virtual void OnRetry() = 0;
     virtual void OnCancel() = 0;
     virtual void OnConfirmationClosed() = 0;
     virtual void OnAdJoined(const std::string& realm) = 0;
     virtual void OnDeviceAttributeProvided(const std::string& asset_id,
                                            const std::string& location) = 0;
   };
 
+  constexpr static OobeScreen kScreenId = OobeScreen::SCREEN_OOBE_ENROLLMENT;
+
   virtual ~EnrollmentScreenView() {}
 
   // Initializes the view with parameters.
   virtual void SetParameters(Controller* controller,
                              const policy::EnrollmentConfig& config) = 0;
 
   // Shows the contents of the screen.
   virtual void Show() = 0;
 
   // Hides the contents of the screen.
@@ skipping 22 matching lines @@
   // Show non-authentication error.
   virtual void ShowOtherError(EnterpriseEnrollmentHelper::OtherError error) = 0;
 
   // Update the UI to report the |status| of the enrollment procedure.
   virtual void ShowEnrollmentStatus(policy::EnrollmentStatus status) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_ENROLLMENT_ENROLLMENT_SCREEN_VIEW_H_