It is often helpful in investigating and debugging rendering and compositing issues to be able to get a snapshot of the RenderLayer tree of a webpage. In OS X WebKit1, this is available through WebRenderLayer. WebKit2 lacks and equivalent API.
Created attachment 131238 [details] Add WKRenderLayer and bundle API for getting the layer tree of a page
Created attachment 131239 [details] Add WKRenderLayer and bundle API for getting the layer tree of a page
Attachment 131239 [details] did not pass style-queue: Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/WebKit2/CMakeLists.txt', u'Source/W..." exit_code: 1 Source/WebKit2/ChangeLog:60: Need whitespace between colon and description [changelog/filechangedescriptionwhitespace] [5] Source/WebKit2/Shared/WebRenderLayer.h:37: Code inside a namespace should not be indented. [whitespace/indent] [4] Source/WebKit2/Shared/WebRenderLayer.h:59: The return type should use PassRefPtr instead of RefPtr. [readability/pass_ptr] [5] Source/WebKit2/Shared/WebRenderLayer.h:60: The return type should use PassRefPtr instead of RefPtr. [readability/pass_ptr] [5] Source/WebKit2/Shared/WebRenderLayer.h:61: The return type should use PassRefPtr instead of RefPtr. [readability/pass_ptr] [5] Source/WebKit2/Shared/WebRenderLayer.h:66: The return type should use PassRefPtr instead of RefPtr. [readability/pass_ptr] [5] Total errors found: 6 in 16 files If any of these errors are false positives, please file a bug against check-webkit-style.
Fixed in <http://trac.webkit.org/r110397>.