Add a screen to migrate filesystem encryption from eCryptfs to ext4 crypto.

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 ba2ae4649e7c21c9f73241aacd8a3ba041ae2f3f..44fbdf5ea06f4881f67545decccfeb5067273800 100644
--- a/chromeos/login/auth/auth_status_consumer.h
+++ b/chromeos/login/auth/auth_status_consumer.h
@@ -120,6 +120,8 @@ class CHROMEOS_EXPORT AuthStatusConsumer {
   virtual void OnOffTheRecordAuthSuccess() {}
   // 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();
 };
 
 }  // namespace chromeos