Additional logs for supervised user auth/creation errors.

chromeos/login/auth/extended_authenticator.cc

Index: chromeos/login/auth/extended_authenticator.cc
diff --git a/chromeos/login/auth/extended_authenticator.cc b/chromeos/login/auth/extended_authenticator.cc
index 549888ddef4c885d65a314b35ac26eb4cc9460aa..1fd02922a68cc293c43065323347f06ee274fa81 100644
--- a/chromeos/login/auth/extended_authenticator.cc
+++ b/chromeos/login/auth/extended_authenticator.cc
@@ -336,6 +336,8 @@ void ExtendedAuthenticator::OnOperationComplete(
     return;
   }
 
+  LOG(ERROR) << "Supervised user cryptohome error, error code: " << return_code;
+
   AuthState state = FAILED_MOUNT;
 
   if (return_code == cryptohome::MOUNT_ERROR_TPM_COMM_ERROR ||