[webkit-changes] [WebKit/WebKit] 7c78af: [UI-side compositing] Mock scrollbars fail to upda...

[Simon Fraser]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7c78af270fc7e11ceed2c6e08cc7390b0a99dced
      https://github.com/WebKit/WebKit/commit/7c78af270fc7e11ceed2c6e08cc7390b0a99dced
  Author: Simon Fraser <simon.fraser at apple.com>
  Date:   2023-05-26 (Fri, 26 May 2023)

  Changed paths:
    M Source/WebCore/platform/Scrollbar.cpp
    M Source/WebCore/platform/Scrollbar.h
    M Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteScrollbarsController.mm

  Log Message:
  -----------
  [UI-side compositing] Mock scrollbars fail to update in many layout tests
https://bugs.webkit.org/show_bug.cgi?id=257398
rdar://109908570

Reviewed by Tim Nguyen.

After 264094 at main we'd fail to issue a repaint in the scrollbar layer in layout tests where
mock scrollers are enabled, so the scrollbar would never update on scrollingcoordinator/mac/multiple-fixed.html
and probably many other tests, with UI-side compositing enabled.

Fix by having RemoteScrollbarsController::shouldDrawIntoScrollbarLayer() ask whether the scrollbar
is a mock scrollbar.

* Source/WebCore/platform/Scrollbar.cpp:
(WebCore::Scrollbar::isMockScrollbar const):
* Source/WebCore/platform/Scrollbar.h:
* Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteScrollbarsController.mm:
(WebKit::RemoteScrollbarsController::shouldDrawIntoScrollbarLayer const):

Canonical link: https://commits.webkit.org/264615@main