Currently, LayerTreeHostGtk flush next frame, after 1/60ms regardless of the rendering time.
Created attachment 198081 [details] Patch
I referenced to AcceleratedCompositingContext in WebKit1
Comment on attachment 198081 [details] Patch Clearing flags on attachment: 198081 Committed r148439: <http://trac.webkit.org/changeset/148439>
All reviewed patches have been landed. Closing bug.