Clean up media header include guards

media/cast/test/skewed_tick_clock.h

Index: media/cast/test/skewed_tick_clock.h
diff --git a/media/cast/test/skewed_tick_clock.h b/media/cast/test/skewed_tick_clock.h
index e9a3a5924e52c1602457d3b6f506d5bf16d209a9..34b267ef5cb5882a06dfbd7ef84f1468a39b0ee9 100644
--- a/media/cast/test/skewed_tick_clock.h
+++ b/media/cast/test/skewed_tick_clock.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
-#define CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
+#ifndef MEDIA_CAST_TEST_SKEWED_TICK_CLOCK_H_
+#define MEDIA_CAST_TEST_SKEWED_TICK_CLOCK_H_
 
 #include "base/macros.h"
 #include "base/time/tick_clock.h"
@@ -42,4 +42,4 @@ class SkewedTickClock : public base::TickClock {
 }  // namespace cast
 }  // namespace media
 
-#endif  // CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
+#endif  // MEDIA_CAST_TEST_SKEWED_TICK_CLOCK_H_