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 60077ec082d0e944523091ef1d2a3514f9fb6a84..8279cbc505ef4a69fd65c563bd6511de33baffc7 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) {}