Some Linux and Mac OS event handler refactoring

runtime/bin/eventhandler.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_EVENTHANDLER_H_
 #define BIN_EVENTHANDLER_H_
 
 #include "bin/builtin.h"
 
-// The event handler delegation class is OS specific.
-#if defined(TARGET_OS_LINUX)
-#include "bin/eventhandler_linux.h"
-#elif defined(TARGET_OS_MACOS)
-#include "bin/eventhandler_macos.h"
-#elif defined(TARGET_OS_WINDOWS)
-#include "bin/eventhandler_win.h"
-#else
-#error Unknown target os.
-#endif
-
 // Flags used to provide information and actions to the eventhandler
 // when sending a message about a file descriptor. These flags should
 // be kept in sync with the constants in socket_impl.dart. For more
 // information see the comments in socket_impl.dart
 enum MessageFlags {
   kInEvent = 0,
   kOutEvent = 1,
   kErrorEvent = 2,
   kCloseEvent = 3,
   kCloseCommand = 8,
   kListeningSocket = 16,
 };
 
 
+// The event handler delegation class is OS specific.
+#if defined(TARGET_OS_LINUX)
+#include "bin/eventhandler_linux.h"
+#elif defined(TARGET_OS_MACOS)
+#include "bin/eventhandler_macos.h"
+#elif defined(TARGET_OS_WINDOWS)
+#include "bin/eventhandler_win.h"
+#else
+#error Unknown target os.
+#endif
+
 class EventHandler {
  public:
   void SendData(intptr_t id, Dart_Port dart_port, intptr_t data) {
     delegate_.SendData(id, dart_port, data);
   }
 
   static EventHandler* StartEventHandler() {
     EventHandler* handler = new EventHandler();
     handler->delegate_.StartEventHandler();
     return handler;
   }
 
  private:
   EventHandlerImplementation delegate_;
 };
 
 
 #endif  // BIN_EVENTHANDLER_H_