cros: Fix MD OOBE crash

chrome/browser/chromeos/login/wizard_controller.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_WIZARD_CONTROLLER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_WIZARD_CONTROLLER_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 354 matching lines @@
   std::string first_screen_name_;
 
   // OOBE/login display host.
   LoginDisplayHost* host_ = nullptr;
 
   // Default WizardController.
   static WizardController* default_controller_;
 
   base::OneShotTimer smooth_show_timer_;
 
-  OobeUI* oobe_ui_ = nullptr;
+  OobeUI* const oobe_ui_;
 
   // State of Usage stat/error reporting checkbox on EULA screen
   // during wizard lifetime.
   bool usage_statistics_reporting_ = true;
 
   // If true then update check is cancelled and enrollment is started after
   // EULA is accepted.
   bool skip_update_enroll_after_eula_ = false;
 
   // The prescribed enrollment configuration for the device.
@@ skipping 60 matching lines @@
   BaseScreen* hid_screen_ = nullptr;
 
   base::WeakPtrFactory<WizardController> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WizardController);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_WIZARD_CONTROLLER_H_