Fix sky include guards to match Chromium style

sky/engine/platform/Length.h

 /*
     Copyright (C) 1999 Lars Knoll (knoll@kde.org)
     Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
     Copyright (C) 2011 Rik Cabanier (cabanier@adobe.com)
     Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 */
 
-#ifndef Length_h
-#define Length_h
+#ifndef SKY_ENGINE_PLATFORM_LENGTH_H_
+#define SKY_ENGINE_PLATFORM_LENGTH_H_
 
 #include <cstring>
 #include "sky/engine/platform/PlatformExport.h"
 #include "sky/engine/platform/animation/AnimationUtilities.h"
 #include "sky/engine/wtf/Assertions.h"
 #include "sky/engine/wtf/FastAllocBase.h"
 #include "sky/engine/wtf/Forward.h"
 #include "sky/engine/wtf/HashMap.h"
 #include "sky/engine/wtf/MathExtras.h"
 #include "sky/engine/wtf/Vector.h"
@@ skipping 308 matching lines @@
         int m_intValue;
         float m_floatValue;
     };
     bool m_quirk;
     unsigned char m_type;
     bool m_isFloat;
 };
 
 } // namespace blink
 
-#endif // Length_h
+#endif  // SKY_ENGINE_PLATFORM_LENGTH_H_