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 180458ee1c7e3949ed8351deddf4c84db590b453..ddb8ab97de0dbbc15f3fdb4e20f2a06f052d91a6 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -266,6 +266,12 @@ 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_;