The logic is basically like so: 1) Is the site requesting a "no-referrer" policy? Then send no referer. 2) Is network.http.sendRefererHeader set to a value

The logic is basically like so: 1) Is the site requesting a "no-referrer" policy? Then send no referer. 2) Is network.http.sendRefererHeader set to a value that would prevent sending of referrer in this situation (e.g. 0 in all situations)? Then send no referrer. 3) All the other logic (but generally aiming to follow the most restrictive directive we have). The "network.http.sendSecureXSiteReferrer" still exists in 50, but is gone in 52; see https://bugzilla.mozilla.org/show_bug.cgi?id=1308725 https://bugzilla.mozilla.org/show_bug.cgi?id=1308725