cc: Ensure pending tree needs prop updates when active tree scrolls.

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 29fc3a33d95a6550b0ee88106773e6cc7a8c4d05..0f92266856ede2ca1f32d04182120ca0fafbe86a 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1221,6 +1221,12 @@ void LayerImpl::DidUpdateScrollOffset(bool is_from_root_delegate) {
     layer_tree_impl()->DidUpdateScrollOffset(id());
   NoteLayerPropertyChangedForSubtree();
   ScrollbarParametersDidChange(false);
+  // Inform the pending twin that a property changed.
+  if (layer_tree_impl()->IsActiveTree()) {
+    LayerImpl* pending_twin = layer_tree_impl()->FindPendingTreeLayerById(id());
+    if (pending_twin)
+      pending_twin->NoteLayerPropertyChangedForSubtree();
+  }
 }
 
 void LayerImpl::SetDoubleSided(bool double_sided) {