WIP - compositor worker mega patch.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index b845968c2f7df709585ad96bda4ce3ecc1bacc71..482a59d638c2a712cbcac7101143ad1789facf71 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1564,6 +1564,11 @@ void LayerImpl::UpdatePropertyTreeScrollOffset() {
 }
 
 void LayerImpl::DidUpdateScrollOffset() {
+  TRACE_EVENT2("compositor-worker,scroll-compensation",
+               "LayerImpl::DidUpdateScrollOffset", "x",
+               scroll_offset_->Current(IsActive()).x(), "y",
+               scroll_offset_->Current(IsActive()).y());
+
   DCHECK(scroll_offset_);
 
   layer_tree_impl()->DidUpdateScrollState(id());