compat: why is eventCounts undefined?

https://developer.mozilla.org/en-US/docs/Web/API/EventCounts

window.EventCounts

Present in FF115+/ESR115, in all window modes, not affected by RFP - so why is TB undefined? AFAICT there is no pref for this - sounds like a compat issue waiting to happen

not a FPing vector (since all users are the same), but tagging it as such to keep track

cc @tjr @pierov

added All Platforms Fingerprinting labels

Gated on dom.enable_event_timing, handled in #40383 (closed).

well, that explains it!

So the original ticket said "Does not clamp measurements" - is this still true since the 60FPS implementation - @tjr - or is there another reason why this should be disabled?

added Needs Information label

assigned to @tjr

https://searchfox.org/mozilla-central/rev/16526d690cccc9c60cacf09cc08e2c3041ef884e/dom/performance/PerformanceEventTiming.cpp#36 makes me think it might not be clamping/jittering in all circumstances. Could you put a bugzilla bug on file for us to investigate?

upstream link 1868770

These timestamps are in fact obeying RFP.

From a RFP leakage POV I do not see anything leaking via dom.enable_event_timing that means that pref needs to stay false.

don't you mean if it's not leaking and is covered by RFP then we can change the pref back to it's default true (by removing our override) ?

Yes, that's correct; thanks.

OK, so that's an easy patch .. any takers .. piero maybe (good first bug ) (it does alter your fingerprint - just look at window properties), but we're already doing that with other patches

Actually yes, I'm in the middle of the alpha rebase and I'm going to lock the branches soon, but maybe we can fit it in.

mentioned in issue #42345 (closed)

removed Needs Information label

added Bug Roadmap::Future Upstream labels

unassigned @tjr

marked this issue as related to #42439

assigned to @pierov

removed Roadmap::Future label

added Doing label

mentioned in merge request !979 (merged)

marked this issue as related to tor-browser-build#41113 (closed)

marked this issue as related to tor-browser-build#41114 (closed)

closed

removed Doing label