There's a new scroll layer now maintained by the common RenderLayerCompositor which applies the scrolling transform. The additional transform added by the LayerRendererChromium should now be removed.
Created attachment 68255 [details] proposed patch updateLayersRecursive is (incorrectly) also called by LayerRendererChromium::prepareToDrawLayers() but the invocation in drawLayers() is the one that really matters. I'll clean up the prepareToDrawLayers() in a separate CL.
Comment on attachment 68255 [details] proposed patch Looks fine to me.
Committed r67966: <http://trac.webkit.org/changeset/67966>