[webkit-changes] [WebKit/WebKit] 92d0cd: [UI-side compositing] Scrolling fails inside an el...

[Simon Fraser]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 92d0cdff8e9e1df0503807e371311c01e28ff0d4
      https://github.com/WebKit/WebKit/commit/92d0cdff8e9e1df0503807e371311c01e28ff0d4
  Author: Simon Fraser <simon.fraser at apple.com>
  Date:   2023-01-07 (Sat, 07 Jan 2023)

  Changed paths:
    M Source/WebKit/UIProcess/RemoteLayerTree/RemoteScrollingCoordinatorProxy.cpp

  Log Message:
  -----------
  [UI-side compositing] Scrolling fails inside an element with a passive wheel event handler
https://bugs.webkit.org/show_bug.cgi?id=250239
rdar://103972021

Reviewed by Tim Horton.

When handling a wheel event inside a region with passive wheel event handlers, we'll
get processing steps `[scrolling thread, main thread non-blocking DOM event dispatch]`.
So we want to handle the scroll in the UI Process, but also send the wheel event to the
web process for DOM event handling.

So only early return in `RemoteScrollingCoordinatorProxy::handleWheelEvent()` when we
don't see the "scrolling thread" step, and make sure we pass the steps to
ScrollingTree::handleWheelEvent() so they get returned in the WheelEventHandlingResult.

* Source/WebKit/UIProcess/RemoteLayerTree/RemoteScrollingCoordinatorProxy.cpp:
(WebKit::RemoteScrollingCoordinatorProxy::handleWheelEvent):

Canonical link: https://commits.webkit.org/258616@main