Fix sky include guards to match Chromium style

sky/engine/platform/image-decoders/gif/GIFImageReader.h

 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
@@ skipping 17 matching lines @@
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-#ifndef GIFImageReader_h
-#define GIFImageReader_h
+#ifndef SKY_ENGINE_PLATFORM_IMAGE-DECODERS_GIF_GIFIMAGEREADER_H_
+#define SKY_ENGINE_PLATFORM_IMAGE-DECODERS_GIF_GIFIMAGEREADER_H_
 
 // Define ourselves as the clientPtr.  Mozilla just hacked their C++ callback class into this old C decoder,
 // so we will too.
 #include "platform/image-decoders/gif/GIFImageDecoder.h"
 #include "sky/engine/platform/SharedBuffer.h"
 #include "sky/engine/wtf/Noncopyable.h"
 #include "sky/engine/wtf/OwnPtr.h"
 #include "sky/engine/wtf/PassOwnPtr.h"
 #include "sky/engine/wtf/Vector.h"
 
@@ skipping 307 matching lines @@
     int m_loopCount; // Netscape specific extension block to control the number of animation loops a GIF renders.
 
     Vector<OwnPtr<GIFFrameContext> > m_frames;
 
     RefPtr<blink::SharedBuffer> m_data;
     bool m_parseCompleted;
 };
 
 } // namespace blink
 
-#endif
+#endif  // SKY_ENGINE_PLATFORM_IMAGE-DECODERS_GIF_GIFIMAGEREADER_H_