When I sign in with google and go to
blogger.com main page pulls in an
accounts.google.com where your login session with Google runs
and you'll notice that it does so using the
passive=true flag which means that it won't prompt you if you're not logged in but it will silently return the result of this request to the caller, in this case
If you're not logged in the HTTP response is:
if you are logged in it will be something like:
<token> represents your user identity in some Google/Blogger specific format.