Fix sky include guards to match Chromium style

sky/engine/core/css/CSSCustomFontData.h

 /*
  * Copyright (C) 2013 Google, Inc.
  *
  * 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 CSSCustomFontData_h
-#define CSSCustomFontData_h
+#ifndef SKY_ENGINE_CORE_CSS_CSSCUSTOMFONTDATA_H_
+#define SKY_ENGINE_CORE_CSS_CSSCUSTOMFONTDATA_H_
 
 #include "sky/engine/core/css/CSSFontFaceSource.h"
 #include "sky/engine/platform/fonts/CustomFontData.h"
 
 namespace blink {
 
 class CSSCustomFontData final : public CustomFontData {
 public:
     enum FallbackVisibility { InvisibleFallback, VisibleFallback };
 
@@ skipping 33 matching lines @@
             m_isLoading = source->isLoading();
     }
 
     RemoteFontFaceSource* m_fontFaceSource;
     FallbackVisibility m_fallbackVisibility;
     mutable bool m_isLoading;
 };
 
 }
 
-#endif // CSSCustomFontData_h
+#endif  // SKY_ENGINE_CORE_CSS_CSSCUSTOMFONTDATA_H_