Move have_wheel_event_handlers to WebLayerTreeView.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 52d33215916e2c8088a4ab911dcc588d2954c1ac..db7247a7415a1d724ef4543272d276ff4f5f5f4e 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -207,6 +207,9 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
 
   void RegisterSelection(const LayerSelection& selection);
 
+  bool have_wheel_event_handlers() const { return have_wheel_event_handlers_; }
+  void SetHaveWheelEventHandlers(bool have_event_handlers);
+
   const LayerTreeSettings& settings() const { return settings_; }
 
   void SetDebugState(const LayerTreeDebugState& debug_state);
@@ -503,6 +506,8 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   SkColor background_color_;
   bool has_transparent_background_;
 
+  bool have_wheel_event_handlers_;
+
   scoped_ptr<AnimationRegistrar> animation_registrar_;
   scoped_ptr<AnimationHost> animation_host_;