The current approach to group all of the URLs related to a single entity (for tracking protection purposes) is to use a pairwise allowlist (bug 1141352). This approach is inefficient (from a bandwidth / memory usage point of view) in the presence of large entities. One proposal (thanks ekr) is to steal a few bits from the blacklist entries to encode an entity ID: https://bugzilla.mozilla.org/show_bug.cgi?id=1141352#c6 Another proposal is to not use the Safe Browsing infrastructure at all for the entity list and instead deliver the list to Firefox using http://kinto.readthedocs.org/en/latest/.

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.