Made top controls work with virtual viewport pinch-to-zoom. (Chromium)

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 172e16f9ad3c88e85cd67a9cdb03954a91966f17..8b42a41dd68fc5b19d99bc1aa754ace9a9139904 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -265,6 +265,12 @@ LayerImpl* LayerTreeImpl::InnerViewportContainerLayer() const {
              : NULL;
 }
 
+LayerImpl* LayerTreeImpl::OuterViewportContainerLayer() const {
+  return outer_viewport_scroll_layer_
+             ? outer_viewport_scroll_layer_->scroll_clip_layer()
+             : NULL;
+}
+
 LayerImpl* LayerTreeImpl::CurrentlyScrollingLayer() const {
   DCHECK(IsActiveTree());
   return currently_scrolling_layer_;