Consolidate ui::NativeEvent and base::NativeEvent

base/message_pump_observer.h

Index: base/message_pump_observer.h
diff --git a/base/message_pump_observer.h b/base/message_pump_observer.h
index d12f2211c4fc9f4e175d86fbbb45eef5a9e23064..efcdebfe1a2b3ecebcfbedb2379f96cec47c5ddd 100644
--- a/base/message_pump_observer.h
+++ b/base/message_pump_observer.h
@@ -4,19 +4,12 @@
 
 #ifndef BASE_MESSAGE_PUMP_OBSERVER_H
 #define BASE_MESSAGE_PUMP_OBSERVER_H
+#pragma once
 
-#if defined(USE_X11)
-typedef union _XEvent XEvent;
-#endif
+#include "base/event_types.h"
 
 namespace base {
 
-#if defined(OS_WIN)
-typedef MSG NativeEvent;
-#elif defined(USE_X11)
-typedef XEvent* NativeEvent;
-#endif
-
 enum EventStatus {
   EVENT_CONTINUE,    // The event should be dispatched as normal.
 #if defined(USE_X11)