The Referrer Policy specification includes three policy values that Chrome doesn't yet implement. - same-origin: Send full referrers same-origin, no referrers cross-origin. - strict-origin: Strip referrers to the origin, but strip them when downgrading from HTTPS to HTTP. - strict-origin-when-cross-origin: Send full referrers same-origin, and the origin when cross-origin, but strip referrers when downgrading from HTTPS to HTTP.