title: Google OAUTH2 - how to detect user is already logged in
body: <p>I'm using Google OAUTH2 for my website. I can successfully login using the google authentication.</p>
  
  <p>Here is what I want to do is:
  1) user goes to website homepage and user signs in by clicking "sign in with google" and login is successful and user is taken to logged user dashboard page.
  2) user comes back after half hour, user goes to home page and they should get automatically redirected to logged in user dashboard instead of homepage since they already have a valid session. </p>
  
  <p>question - how can you detect if the user is already logged in? Should I be storing the access_token in the session to detect this? what's the recommended way to acheive this with Google OAUTH2? </p>