Fix sky include guards to match Chromium style

sky/engine/core/css/HashTools.h

 /*
  * Copyright (C) 2010 Andras Becsi <abecsi@inf.u-szeged.hu>, University of Szeged
  *
  * 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 HashTools_h
-#define HashTools_h
+#ifndef SKY_ENGINE_CORE_CSS_HASHTOOLS_H_
+#define SKY_ENGINE_CORE_CSS_HASHTOOLS_H_
 
 namespace blink {
 
 struct Property {
     int nameOffset;
     int id;
 };
 
 struct Value {
     int nameOffset;
     int id;
 };
 
 const Property* findProperty(register const char* str, register unsigned len);
 const Value* findValue(register const char* str, register unsigned len);
 
 } // namespace blink
 
-#endif // HashTools_h
+#endif  // SKY_ENGINE_CORE_CSS_HASHTOOLS_H_