… the scene builder thread. r=jrmuizel

Instead of collecting so-called ipc counters when receving the SetDisplayList on the render backend, pass the information through the scene builder thread and update the profile on the render backend after the scene is swapped. This prevents ipc counters to be displayed while the transaction is still being processed by the scene builder thread.

Differential Revision: https://phabricator.services.mozilla.com/D69414

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/1a729c8ea63134fb2746cad5639cde022ea4919b