1183420 - Clean up fullscreen permission from permission database

Status: RESOLVED WONTFIX

(Core :: Permission Manager, defect, P5)

Description

[Xidorn Quan [:xidorn] UTC+10]

After we land bug 1160017, fullscreen will no longer need any approval. Thus the fullscreen-related data in the permission database will be useless then. We should clean them up.

But as Firefox in several channels share the same profile, we probably want to do it only after bug 1160017 reaches release channel or even esr channel.

Comment 1

[Dan Mehic]

The fullscreen permission type has been unreferenced in the tree since bug
1160017 landed in Firefox 42, which removed the approval requirement along with
every reader and writer of the type. There are no consumers left in
mozilla-central today.

The stale data this bug describes is real, not hypothetical. The approval
prompt's "Remember decision" checkbox wrote an EXPIRE_NEVER permission via
Services.perms.add(uri, "fullscreen", ...), and full-screen-api.approval-required
defaulted to true from bug 716107 (Firefox 10) until it was removed in 42. So
profiles from that era can still carry rows in moz_perms.

That said, the affected population is profiles continuously migrated since
November 2015 whose user also ticked a checkbox that defaulted to unchecked, and
the rows are inert: nothing reads the type and no UI surfaces it. Cleaning them
up means spending a permissions DB schema version on a migration that every
profile walks through, plus a case in PermissionManager.cpp's migration switch
to maintain indefinitely, for no user-visible benefit. Ten years on, that trade
no longer looks worth it.

Resolving as WONTFIX. If a permissions schema bump happens for some other
reason, folding a DELETE FROM moz_perms WHERE type = 'fullscreen' into that
migration is nearly free and would be a reasonable thing to do at the time.