Skia draws its rounded corners differently from the other ports. Whereas they have anti-aliased clipping regions, Skia only has 1-bit regions. (Which is technically more correct, but somewhat unhelpful for us.) Instead, with Skia we use a layer and collect all the clipping paths in effect. When the state is popped, we paint transparency outside the clipping paths and merge the layer down. This appears to cause rounded borders to look a little thin, which is addressed in this patch. This is well covered by existing tests but will require new baselines in the Chromium tree.
Created attachment 43668 [details] patch (Note: please don't cq+ this patch.)
Comment on attachment 43668 [details] patch Marking cq- per Adam's note above.
Comment on attachment 43668 [details] patch LGTM. CC'd brett so he sees this go by.
Comment on attachment 43668 [details] patch Setting commit-queue+ as we are ready on Chromium side for this to land.
Comment on attachment 43668 [details] patch Clearing flags on attachment: 43668 Committed r51722: <http://trac.webkit.org/changeset/51722>
All reviewed patches have been landed. Closing bug.