It's exactly the same as Nicosia::CompositionLayer::accessPending() which is more explicit and less confusing.
Pull request: https://github.com/WebKit/WebKit/pull/5902
Committed 256141@main (693343741daa): <https://commits.webkit.org/256141@main> Reviewed commits have been landed. Closing PR #5902 and removing active labels.
<rdar://problem/101729477>