Use the Primary Password is a technology to protect cookie and password fire fox could bring this technology to the opera this it can prevent the virus from stealing cookies from websites like gmail, banks etc.
click on the link below for more information: https://support.mozilla.org/en-US/kb/use-primary-password-protect-stored-logins?as=u&utm_source=inproduct&redirectslug=use-master-password-protect-stored-logins&redirectlocale=en-US