title: How do I detect an invalid auth token from chrome.identity.getAuthToken()?
body: <p>The onInstall hook for my extension calls chrome.identity.getAuthToken(). If this is the first time I've run the app, all works OK.</p>
  
  <p>The issue I have is that during testing, I am revoking access and then re-installing the extension. In this scenario, getAuthToken() is returning the cached, invalid token. Some time later, my extension is failing 401 when I try to use the extension. What I want to do is to detect that the extension has come from the cache, and immediately remove it so I can do the auth dialogue. If I could access the token expiration time, I could deduce its validity, but afaik, the expiration time isn't visible.</p>
  
  <p>Any suggestions on how to code around this?</p>