title: How to refresh expired google sign-in logins?
body: <p>I'm using Google Sign-In. A user comes to my site and logs in with <code>gapi.auth2.getAuthInstance().signIn()</code>, or they are already logged in and when the page loads (or reloads) we fetch the status. At this point I have an identity token good for an hour that I can validate on the server.</p>
  
  <p>When a user leaves the browser sitting (say, overnight), this token expires. <code>gapi.auth2.getAuthInstance().isSignedIn.get()</code> returns true, but the token does not validate.</p>
  
  <p>How can I log in a user and keep them logged in while their session is active (ie, browser hasn't been closed)? Or refresh the token? Anything more graceful than reloading the page...</p>
  
  <p>Edit: The refresh token is not a correct answer; I don't want offline access (and don't want to ask for the permission). Google obviously thinks the user is still signed into my application; the user can reload the page and get a new token without providing credentials again. Surely there is some mechanism more graceful than a hidden iframe to get an updated token?</p>