Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

cc/trees/layer_tree_host_client.h

Index: cc/trees/layer_tree_host_client.h
diff --git a/cc/trees/layer_tree_host_client.h b/cc/trees/layer_tree_host_client.h
index 03c2431f87476bcb135709d2745313b6e735d33d..84416d60ef01c5cd173116ab7b64ab8955f8cf65 100644
--- a/cc/trees/layer_tree_host_client.h
+++ b/cc/trees/layer_tree_host_client.h
@@ -58,6 +58,10 @@ class LayerTreeHostClient {
   virtual void DidCommitAndDrawFrame() = 0;
   virtual void DidReceiveCompositorFrameAck() = 0;
   virtual void DidCompletePageScaleAnimation() = 0;
+  // The only time a subframe ever gets its own LayerTree is when the subframe
+  // renders in a different process its ancestors; this returns true in
+  // that case.
+  virtual bool IsForSubframe() = 0;
 
  protected:
   virtual ~LayerTreeHostClient() {}