Respect the order of input messages from browser to renderer

content/renderer/input/input_handler_manager.h

Index: content/renderer/input/input_handler_manager.h
diff --git a/content/renderer/input/input_handler_manager.h b/content/renderer/input/input_handler_manager.h
index 3403b82c5999d334dc61ac5ba7eb4d8b5ee61550..bdcaceca1d0880b8475cac977c663e3b288e8104 100644
--- a/content/renderer/input/input_handler_manager.h
+++ b/content/renderer/input/input_handler_manager.h
@@ -59,6 +59,9 @@ class CONTENT_EXPORT InputHandlerManager {
                        bool enable_smooth_scrolling,
                        bool enable_wheel_gestures);
 
+  void RegisterRoutingID(int routing_id);
+  void UnregisterRoutingID(int routing_id);
+
   void ObserveWheelEventAndResultOnMainThread(
       int routing_id,
       const blink::WebMouseWheelEvent& wheel_event,
@@ -101,6 +104,9 @@ class CONTENT_EXPORT InputHandlerManager {
       bool enable_smooth_scrolling,
       bool enable_wheel_gestures);
 
+  void RegisterRoutingIDOnCompositorThread(int routing_id);
+  void UnregisterRoutingIDOnCompositorThread(int routing_id);
+
   void ObserveWheelEventAndResultOnCompositorThread(
       int routing_id,
       const blink::WebMouseWheelEvent& wheel_event,