Clean up media header include guards

media/cast/test/utility/net_utility.h

 // Copyright 2014 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 MEDIA_CAST_TEST_UTILITY_NET_UTILITY_H_
+#define MEDIA_CAST_TEST_UTILITY_NET_UTILITY_H_
+
 #include "net/base/ip_endpoint.h"
 
 namespace media {
 namespace cast {
 namespace test {
 
 // Determine a unused UDP port for the in-process receiver to listen on.
 // Method: Bind a UDP socket on port 0, and then check which port the
 // operating system assigned to it.
 net::IPEndPoint GetFreeLocalPort();
 
 }  // namespace test
 }  // namespace cast
 }  // namespace media
+
+#endif  // MEDIA_CAST_TEST_UTILITY_NET_UTILITY_H_