https://bugs.webkit.org/show_bug.cgi?id=228936 (Notify accessibility that WebProcess is suspended when in process cache) added an accessibility notification that a process is suspended, but only for iOS. We need the same notification on macOS also. The Mac implementation of the notification is already there, and it's already used in other places in the code where a process is suspended. We were just missing the case where the process gets added to the process cache. The bug this causes is that assistive technology can try to query attributes of an element that's in the suspended process. The query hangs until it times out. This was happening sometimes when following a link to a different domain with VoiceOver. The notification enables accessibility clients to keep track of which processes are suspended and cause any queries to those processes to fail fast.
<rdar://problem/129796427>
Pull request: https://github.com/WebKit/WebKit/pull/29793
Committed 280077@main (f1b8127093df): <https://commits.webkit.org/280077@main> Reviewed commits have been landed. Closing PR #29793 and removing active labels.