Turn off computation of the interest rect in cc in synchronized paint mode.

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 36d56f26ebb6644e024eb215bca060aa7d2f67fd..65b1f024ea32b507ac0bfa1ef4fff460173dd4c1 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -750,6 +750,10 @@ void Layer::RequestCopyOfOutput(scoped_ptr<cc::CopyOutputRequest> request) {
   cc_layer_->RequestCopyOfOutput(request.Pass());
 }
 
+gfx::Rect Layer::PaintableRegion() {
+  return bounds();
+}
+
 scoped_refptr<cc::DisplayItemList> Layer::PaintContentsToDisplayList(
     const gfx::Rect& clip,
     ContentLayerClient::PaintingControlSetting painting_control) {