Fix sky include guards to match Chromium style

sky/engine/core/css/StyleSheetContents.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. 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 StyleSheetContents_h
-#define StyleSheetContents_h
+#ifndef SKY_ENGINE_CORE_CSS_STYLESHEETCONTENTS_H_
+#define SKY_ENGINE_CORE_CSS_STYLESHEETCONTENTS_H_
 
 #include "sky/engine/core/css/RuleSet.h"
 #include "sky/engine/platform/heap/Handle.h"
 #include "sky/engine/platform/weborigin/KURL.h"
 #include "sky/engine/wtf/HashMap.h"
 #include "sky/engine/wtf/ListHashSet.h"
 #include "sky/engine/wtf/RefCounted.h"
 #include "sky/engine/wtf/Vector.h"
 #include "sky/engine/wtf/text/AtomicStringHash.h"
 #include "sky/engine/wtf/text/StringHash.h"
@@ skipping 122 matching lines @@
 
     HashSet<RawPtr<CSSStyleSheet> > m_loadingClients;
     HashSet<RawPtr<CSSStyleSheet> > m_completedClients;
     typedef HashSet<RawPtr<CSSStyleSheet> >::iterator ClientsIterator;
 
     OwnPtr<RuleSet> m_ruleSet;
 };
 
 } // namespace
 
-#endif
+#endif  // SKY_ENGINE_CORE_CSS_STYLESHEETCONTENTS_H_