[UnfiedPDF] Flicker of low-resolution content when toggling a checkbox

[smfr]

5ab3ad6

[UnfiedPDF] Flicker of low-resolution content when toggling a checkbox
https://bugs.webkit.org/show_bug.cgi?id=273912
rdar://127773717

Reviewed by Abrar Rahman Protyasha.

The fine-grained tile invalidation added in 277837@main adds a check on the "contentVersion",
which increments whenever an annotation, like a checkbox, changes state. This caused us to
throw away rendered tiles in `AsyncPDFRenderer::willRepaintTile()`, which resulted in a flash
of the blurry page background until we got the new tile.

It's OK to paint tiles with a stale contentVersion; we'll paint the new state once we've got
a rendered tile with the new content.

* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/AsyncPDFRenderer.h:
(WebKit::AsyncPDFRenderer::TileRenderInfo::equivalentForPaintingIgnoringContentVersion const):
* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/AsyncPDFRenderer.mm:
(WebKit::AsyncPDFRenderer::renderInfoIsValidForTile const):
(WebKit::AsyncPDFRenderer::willRepaintTile):
(WebKit::AsyncPDFRenderer::didCompleteTileRender):

Canonical link: https://commits.webkit.org/278544@main

7c72dfb

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt		✅ 🛠 wpe-skia
	🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 7c72dfb)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt		✅ 🛠 wpe-skia
	🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 278544@main (5ab3ad6): https://commits.webkit.org/278544@main

Reviewed commits have been landed. Closing PR #28312 and removing active labels.