Clean up media header include guards

media/cast/test/utility/test_util.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_TEST_UTIL_H
-#define MEDIA_CAST_TEST_UTILITY_TEST_UTIL_H
+#ifndef MEDIA_CAST_TEST_UTILITY_TEST_UTIL_H_
+#define MEDIA_CAST_TEST_UTILITY_TEST_UTIL_H_
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
 
 namespace media {
 namespace cast {
 namespace test {
 
 class MeanAndError {
  public:
   MeanAndError() {}
   explicit MeanAndError(const std::vector<double>& values);
   std::string AsString() const;
 
   size_t num_values;
   double mean;
   double std_dev;
 };
 
 }  // namespace test
 }  // namespace cast
 }  // namespace media
 
-#endif  // MEDIA_CAST_TEST_UTILITY_TEST_UTIL_H
+#endif  // MEDIA_CAST_TEST_UTILITY_TEST_UTIL_H_