Few months ago, Google changed sign-in procedure internally to support switch multiple accounts easily. This is nice, but if you sign-in with checked "Stay signed in", Google saved your account information into cookie and it remain after sign-out. As a result, Everybody can see your account id on google sign-in page. This is not good in shared PC. Therefor I created this addon to remove cookie that related to account chooser automatically. [FYI] When you try to sign-in Web site that is using the "Mozilla Persona" for user authentication ("Mozilla Developer Network" and "bugzilla" for example) with Gmail address. You have to sign-in to Google in the middle of authentication. At that time, the check box that says "Stay signed in" does not appear on the Google sign-in page. But it is treated as the check box is checked to "Stay signed in" state Internally . As a result, Google saved your account information into cookie and it remain after sign-out. P.S. Maybe my other addon "Uncheck Stay-signed-in for Google Login" will help to protect your privacy. https://addons.mozilla.org/firefox/addon/uncheck-stay-signed-in/ Important Information: 2016/03/16 Mozilla is changing a lot of things about add-on development again. So this addon might be stop working in the future.

"The Future of Developing Firefox Add-ons | Mozilla Add-ons Blog" https://blog.mozilla.org/addons/2015/08/21/the-future-of-developing-firefox-add-ons/ "Add-ons/developer/communication - MozillaWiki - Upcoming Changes in Add-on Development"https://wiki.mozilla.org/Add-ons/developer/communication#Upcoming_Changes_in_Add-on_Development