Comment 4 for bug 1605218

To confirm, you can use a guest session, and re-do the test here. You will not be logged in automatically after a browser restart, due to the use of session cookies by the Google Account service.

As pointed out by mardy, the behavior observed in the bug report is due to a chrome feature called "continue where you left off", where chrome doesn't delete the session cookies used for storing that (temporary) username variable.

Ref: http://stackoverflow.com/questions/10617954/chrome-doesnt-delete-session-cookies