Implement a basic UI flow for cryptohome encryption migration.

chromeos/login/auth/auth_status_consumer.h

Index: chromeos/login/auth/auth_status_consumer.h
diff --git a/chromeos/login/auth/auth_status_consumer.h b/chromeos/login/auth/auth_status_consumer.h
index 44fbdf5ea06f4881f67545decccfeb5067273800..86c1b579b5ea765eecd07d31c0fc5aeff7e5ceaf 100644
--- a/chromeos/login/auth/auth_status_consumer.h
+++ b/chromeos/login/auth/auth_status_consumer.h
@@ -121,7 +121,7 @@ class CHROMEOS_EXPORT AuthStatusConsumer {
   // The same password didn't work both online and offline.
   virtual void OnPasswordChangeDetected();
   // The cryptohome is encrypted in old format and needs migration.
-  virtual void OnOldEncryptionDetected();
+  virtual void OnOldEncryptionDetected(const UserContext& user_context);
 };
 
 }  // namespace chromeos