Convert Aura to use ui::Event.

ui/aura/event_mac.h

Index: ui/aura/event_mac.h
===================================================================
--- ui/aura/event_mac.h	(revision 150582)
+++ ui/aura/event_mac.h	(working copy)
@@ -1,18 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef UI_AURA_EVENT_MAC_H_
-#define UI_AURA_EVENT_MAC_H_
-
-#include "base/event_types.h"
-
-namespace aura {
-
-// Returns a deep copy of the native |event|.  On Mac the returned value is
-// autoreleased.
-base::NativeEvent CopyNativeEvent(const base::NativeEvent& event);
-
-}  // namespace aura
-
-#endif  // UI_AURA_EVENT_MAC_H_