services/etc/media_service_bionic.cfg

{
    "services" : [{
            "name" : "media_service",
            "path" : ["/system/bin/sa_main", "/system/profile/media_service.xml"],
            "uid" : "media",
            "gid" : ["media_rw", "system", "root"],
            "secon" : "u:r:media_service:s0"
        }
    ]
}