Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

cc/trees/layer_tree_settings.h

Index: cc/trees/layer_tree_settings.h
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index d54e05c060cf6e450b52707dd6940f6f24edb924..b914f230ac72f3cfe2feee8f7f88b7327a8bf61a 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -110,6 +110,8 @@ class CC_EXPORT LayerTreeSettings {
   // Indicates that the LayerTreeHost should defer commits unless it has a valid
   // LocalSurfaceId set.
   bool needs_valid_local_surface_id = false;
+
+  bool is_layer_tree_for_subframe = false;
 };
 
 }  // namespace cc