tree c7c60806f2eb831cf8e768345f29d29ff69e03ec
parent 404ccb247e1a7e6cb5fc405b69369a4ad9acdda1
author David Bokan <bokan@chromium.org> 1641431938 -0800
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> 1641432806 -0800

Fix visual viewport scroll event ordering

This change ensures the DOMWindow scroll event is fired before the
VisualViewport scroll event if both are scrolled in the same rAF. We do
this in DistributeScrollBetweenViewports which can distribute scroll
to either viewport first (though usually it's the visual viewport). This
method now computes the offset distribution based on the `scroll_first`
argument but always applies the scroll to the layout viewport first in
so that the event dispatch works in the correct order.

Added WPT for to ensure this ordering for both scroll and resize events.
The resize event behavior was fixed inadvertently in
https://crrev.com/ae16ed0d42708721662e6b4382659222ccddcf3d.

See https://github.com/WICG/visual-viewport/issues/65 and
https://github.com/WICG/visual-viewport/issues/66

Bug: 1016210
Change-Id: Ibb241cf27d163b7dfe4d83b9f65bf172d7f38769
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3359003
Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#955982}