IPC::ParamTraits for ui::Event (towards ui::Events over mojo IPC)

ui/events/event.cc

Index: ui/events/event.cc
diff --git a/ui/events/event.cc b/ui/events/event.cc
index 6e1228c82d83b171518e0e71b81ce9af67ec3a91..9c7561469369a97f2f74030bcd31778990914b31 100644
--- a/ui/events/event.cc
+++ b/ui/events/event.cc
@@ -747,6 +747,9 @@ bool KeyEvent::IsRepeated(const KeyEvent& event) {
   return false;
 }
 
+KeyEvent::KeyEvent(EventType type, base::TimeDelta time_stamp, int flags)
+    : Event(type, time_stamp, flags) {}
+
 KeyEvent::KeyEvent(const base::NativeEvent& native_event)
     : Event(native_event,
             EventTypeFromNative(native_event),