Implement a basic UI flow for cryptohome encryption migration.

chrome/browser/chromeos/login/screens/encryption_migration_screen_view.h

 // Copyright 2017 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_SCREENS_ENCRYPTION_MIGRATION_SCREEN_VIEW_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_ENCRYPTION_MIGRATION_SCREEN_VIEW_H_
 
 #include "chrome/browser/chromeos/login/oobe_screen.h"
 
 namespace chromeos {
 
+class UserContext;
+
 class EncryptionMigrationScreenView {
  public:
   class Delegate {
    public:
     virtual ~Delegate() {}
 
     // Called when screen is exited.
     virtual void OnExit() = 0;
 
     // This method is called, when view is being destroyed. Note, if Delegate is
     // destroyed earlier then it has to call SetDelegate(NULL).
     virtual void OnViewDestroyed(EncryptionMigrationScreenView* view) = 0;
   };
 
   constexpr static OobeScreen kScreenId =
       OobeScreen::SCREEN_ENCRYPTION_MIGRATION;
 
   virtual ~EncryptionMigrationScreenView() {}
 
   virtual void Show() = 0;
   virtual void Hide() = 0;
   virtual void SetDelegate(Delegate* delegate) = 0;
+  virtual void SetUserContext(const UserContext& user_context) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_ENCRYPTION_MIGRATION_SCREEN_VIEW_H_