Starting with the Chrome 25, Chrome will disable silently installed third-party bundled extensions. Additionally, all sideloaded extensions will be disabled once including those installed manually by the users.
Google Chrome team has decided to implement a similar feature in Chrome, which although allows installation of external extensions, but disables them by default. Users are notified about this change, and prompted to enable or uninstall such extensions.
Thanks to the rapid release cycle of Firefox, the open source browser has hit the version number 9 which is available through the nightly channel.
Mozilla has announced to disable all third party bundled add-ons by default. Users are required to enable such add-ons manually in order to use these add-ons.