The Chromium project imposes additional requirements on the OWNERS of certain security-sensitive areas of the codebase. Whether these requirements are met is judged by a council of senior security engineers, who are listed in [../../SECURITY_OWNERS](the root SECURITY_OWNERS file).
The specific requirements are:
To add a new user to a SECURITY_OWNERS file anywhere in the tree, prepare a CL adding that user to the file, then send it to one of the members of //SECURITY_OWNERS for review as normal. The root SECURITY_OWNERS will discuss amongst themselves, then either approve or disapprove your CL.