Fix sky include guards to match Chromium style

sky/engine/platform/text/StringTruncator.h

 /*
  * Copyright (C) 2005, 2006, 2007 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.
  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE 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 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
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  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef StringTruncator_h
-#define StringTruncator_h
+#ifndef SKY_ENGINE_PLATFORM_TEXT_STRINGTRUNCATOR_H_
+#define SKY_ENGINE_PLATFORM_TEXT_STRINGTRUNCATOR_H_
 
 #include "sky/engine/platform/PlatformExport.h"
 #include "sky/engine/wtf/Forward.h"
 
 namespace blink {
 
 class Font;
 
 class PLATFORM_EXPORT StringTruncator {
 public:
     static String centerTruncate(const String&, float maxWidth, const Font&);
     static String rightTruncate(const String&, float maxWidth, const Font&);
     static float width(const String&, const Font&);
 };
 
 } // namespace blink
 
-#endif // !defined(StringTruncator_h)
+#endif  // SKY_ENGINE_PLATFORM_TEXT_STRINGTRUNCATOR_H_