Normally, we'd resort to direct rendering when the backing store is not active. However, direct rendering is broken with OpenGL compositing code path, and we have a better option anyway - use accelerated compositing layer to render the root layer instead of backing store. This will give us a tiled layer backing the root layer. This in turn will enable multiple web pages to be composited at once with the new WebPageCompositor API.
Created attachment 135536 [details] Patch
I think this patch could use an internal reviewer as well as an external, since I think this is not Antonio or Rob's area of expertise. But you're certainly welcome to do it if you feel up to the task =)
The patch looks great to me
Created attachment 135800 [details] Patch
(In reply to comment #4) > Created an attachment (id=135800) [details] > Patch ChangeLog entry updated with the fact that it was reviewed internally by Filip Spacek. Ready for external review =)
Comment on attachment 135800 [details] Patch Second r+!
Comment on attachment 135800 [details] Patch This can be landed indepently of the webcore patch we're depending on. I'll just remove the dependency.
Comment on attachment 135800 [details] Patch Clearing flags on attachment: 135800 Committed r113325: <http://trac.webkit.org/changeset/113325>
All reviewed patches have been landed. Closing bug.