tree bf39509c7a9c3fba8a8895d86b80e942cd5a3913
parent 1cdd682a491f3301445ee0dadc312bf53b2ae851
author Philip Rogers <pdr@chromium.org> 1637019657 -0800
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> 1637020114 -0800

Do not skip compositing update for non-animation transform changes

Properties like "will-change: transform" are direct compositing reasons
which let us skip raster when properties change. Usually, we still need
to update compositing when directly-composited transforms change because
overlap can change. An exception to this is animations which assume
worst-case overlap in |PendingLayer::VisualRectForOverlapTesting|. This
patch stops skipping the compositing update for non-animation transform
changes.

An alternative approach of assuming worst-case overlap for will-change
transform was investigated in https://crrev.com/c/3280439 but this has
two downsides: complexity and compositing memory (a good example is
composited-scroll-overlap-test.html). Before CompositeAfterPaint, we
would need to run compositing as well, so the approach in this patch
has precedent. We may want to expand the visual rect for
will-change: transform in the future, for performance parity with
animations.

Bug: 1267689
Change-Id: I9812426e9a159bdbe44476390e10fe53478f9ccc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3282945
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#941904}