title: Detecting connectivity with the Drive Realtime API
body: <p>I want to display a message when my user is offline and disable all editing features, then reenable them when the user comes back online.  Right now I'm using navigator.onLine which doesn't actually detect connectivity very well in some cases.  </p>
  
  <p>What's the best way to determine whether the Drive Realtime API is connected?</p>