Adding reviewers overrides the GerritCallback onFailure event handler and doesn't check the normal cases for a signed out user. Since the error handling should display a message below the field and not a dialog, we can't use the parent class, but we can use the helper methods to at least determine when to display the signed-out dialog. Change-Id: Ie25efc014cc106373664b3ddf26122d4c73c7928