Remove IPC::ParamTraits for ui::Event.

ui/events/gesture_event_details.h

Index: ui/events/gesture_event_details.h
diff --git a/ui/events/gesture_event_details.h b/ui/events/gesture_event_details.h
index 1bc283fba4f78a27874d97d6228e9562e83dc980..377c4232c991e3c0d580002421667ce311b69bfa 100644
--- a/ui/events/gesture_event_details.h
+++ b/ui/events/gesture_event_details.h
@@ -13,10 +13,6 @@
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 
-namespace IPC {
-template <class P> struct ParamTraits;
-}
-
 namespace ui {
 
 struct EVENTS_BASE_EXPORT GestureEventDetails {
@@ -202,10 +198,6 @@ struct EVENTS_BASE_EXPORT GestureEventDetails {
     int tap_count;  // TAP repeat count.
   } data_;
 
-  // For mojo native implementation of (de)serialization.
-  friend struct IPC::ParamTraits<ui::GestureEventDetails>;
-  friend struct IPC::ParamTraits<ui::GestureEventDetails::Details>;
-
   GestureDeviceType device_type_;
 
   int touch_points_;  // Number of active touch points in the gesture.