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 b6237c944470e3f34e38626e90b80eede5ae90cd..996d6279fec606adbca0a193de0e998d22f46250 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -110,6 +110,10 @@ class CC_EXPORT LayerTreeSettings {
   // Indicates that the LayerTreeHost should defer commits unless it has a valid
   // LocalSurfaceId set.
   bool enable_surface_synchronization = false;
+
+  // Indicates the case when a sub-frame gets its own LayerTree because it's
+  // rendered in a different process from its ancestor frames.
+  bool is_layer_tree_for_subframe = false;
 };
 
 }  // namespace cc