Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

cc/test/layer_tree_test.cc

Index: cc/test/layer_tree_test.cc
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index 4545cfddd95e854bb1842a063fb365280aaf8262..565205376b1220ed7e33602043cd08a3d02d8e1b 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -358,6 +358,8 @@ class LayerTreeHostClientForTesting : public LayerTreeHostClient,
     test_hooks_->BeginMainFrameNotExpectedSoon();
   }
 
+  bool IsForSubframe() override { return false; }
+
  private:
   explicit LayerTreeHostClientForTesting(TestHooks* test_hooks)
       : test_hooks_(test_hooks) {}