Move scroll event handlers from layer to layer tree view.

content/test/web_layer_tree_view_impl_for_testing.h

Index: content/test/web_layer_tree_view_impl_for_testing.h
diff --git a/content/test/web_layer_tree_view_impl_for_testing.h b/content/test/web_layer_tree_view_impl_for_testing.h
index 990ef07c1692ac643b6f617a197b4a328bbd01ca..b0cf969f4c6f58687d01aa0dab11733b46c4b796 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.h
+++ b/content/test/web_layer_tree_view_impl_for_testing.h
@@ -70,6 +70,8 @@ class WebLayerTreeViewImplForTesting
 
   void setHaveWheelEventHandlers(bool have_event_handlers) override;
   bool haveWheelEventHandlers() const override;
+  void setHaveScrollEventHandlers(bool) override;
+  bool haveScrollEventHandlers() const override;
 
   // cc::LayerTreeHostClient implementation.
   void WillBeginMainFrame() override {}