Pin Code or password Access for settings and extensions.
I recommend a feature allowing users to lock access to the settings and extensions tabs.
This feature will allow parents or administrators to restrict access to the settings tab or restrict browser extensions from being installed.
Some additional security for stopping unwanted setting changes and blocking the ability to install unwanted or insecure extensions.
This would be more of a deterrent rather then security.
however this could potentially be something to help protect against browser cloning.