[webkit-changes] [WebKit/WebKit] c23146: Lyrics jump around in Spotify

[Simon Fraser]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: c2314679be38e362cb9f6fbe7ad9c21aabfecbc1
      https://github.com/WebKit/WebKit/commit/c2314679be38e362cb9f6fbe7ad9c21aabfecbc1
  Author: Simon Fraser <simon.fraser at apple.com>
  Date:   2023-11-01 (Wed, 01 Nov 2023)

  Changed paths:
    A LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-expected.txt
    A LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-overflow-expected.txt
    A LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-overflow.html
    A LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero.html
    M Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.cpp
    M Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm
    M Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.mm

  Log Message:
  -----------
  Lyrics jump around in Spotify
https://bugs.webkit.org/show_bug.cgi?id=263946
rdar://116843612

Reviewed by Tim Horton.

The `RequestedScrollData` that's processed on the scrolling thread or in the UI process for a programmatic
scroll can contain secondary data that says what to do before starting an animated scroll, in
`requestedDataBeforeAnimatedScroll`.

The three places that process this data were failing to take into account the `ScrollRequestType::CancelAnimatedScroll`
request type, which resulted in using `positionOrDeltaBeforeAnimatedScroll` to do an initial non-animated
scroll, which would always end up as 0,0 thus triggering the scroll to top behavior.

* LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-expected.txt: Added.
* LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-overflow-expected.txt: Added.
* LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero-overflow.html: Added.
* LayoutTests/fast/scrolling/cancel-animated-scroll-should-not-scroll-from-zero.html: Added.
* Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.cpp:
(WebCore::ScrollingTreeScrollingNode::handleScrollPositionRequest):
* Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm:
(WebKit::RemoteLayerTreeDrawingAreaProxy::commitLayerTreeTransaction):
* Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.mm:
(WebKit::RemoteScrollingTreeMac::startPendingScrollAnimations):

Canonical link: https://commits.webkit.org/270077@main