Fix sky include guards to match Chromium style

sky/engine/wtf/NullPtr.h

 /*
 
 Copyright (C) 2010 Apple Inc. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1.  Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
 2.  Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
 
 THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 */
 
-#ifndef NullPtr_h
-#define NullPtr_h
+#ifndef SKY_ENGINE_WTF_NULLPTR_H_
+#define SKY_ENGINE_WTF_NULLPTR_H_
 
 // libstdc++ supports nullptr_t starting with gcc 4.6. STLport doesn't define it.
 #if (defined(__GLIBCXX__) && __GLIBCXX__ < 20110325) || defined(_STLPORT_VERSION)
 namespace std {
 typedef decltype(nullptr) nullptr_t;
 }
 #endif
 
 #define WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(ClassName) \
     private: \
         ClassName(int) = delete
 #define WTF_DISALLOW_ZERO_ASSIGNMENT(ClassName) \
     private: \
         ClassName& operator=(int) = delete
 
-#endif
+#endif  // SKY_ENGINE_WTF_NULLPTR_H_