[webkit-changes] [WebKit/WebKit] 969229: [Site Isolation][iOS] Do not recreate hosting laye...

[Sihui]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 9692297b2f37a9eb1dba6401b6781f33ddb7a1f4
      https://github.com/WebKit/WebKit/commit/9692297b2f37a9eb1dba6401b6781f33ddb7a1f4
  Author: Sihui Liu <sihui_liu at apple.com>
  Date:   2024-02-02 (Fri, 02 Feb 2024)

  Changed paths:
    M Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
    M Source/WebCore/platform/graphics/ca/PlatformCALayer.h
    M Source/WebKit/WebProcess/WebPage/RemoteLayerTree/PlatformCALayerRemoteHost.h

  Log Message:
  -----------
  [Site Isolation][iOS] Do not recreate hosting layer when hosting identifier has no change
https://bugs.webkit.org/show_bug.cgi?id=268642
rdar://122195472

Reviewed by Alex Christensen.

When running site isolation tests, I noticed there were many PlatformCALayers created even though the frame tree did
not change. I found that GraphicsLayerCA resets its m_contentsLayer every time RenderLayerBacking::updateConfiguration
is invoked. This is unnecessary as the new contents layer has the same configuration as the old one when hosting
identifier does not change.

* Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp:
(WebCore::GraphicsLayerCA::setContentsToPlatformLayerHost):
* Source/WebCore/platform/graphics/ca/PlatformCALayer.h:
* Source/WebKit/WebProcess/WebPage/RemoteLayerTree/PlatformCALayerRemoteHost.h:

Canonical link: https://commits.webkit.org/274028@main