title: Get google accounts signed into browser with a Chrome Extension
body: <p>Google uses something like <code>?authuser=X</code> at the end of URL to determine the google account.
  Is there some way to list all the signed-in accounts on the browser with their number X?</p>
  <p>I am trying to make the user choose the account they want and then get the X, using chrome.identity does still not give X</p>