Fix ALL the include guards.

core/src/fxcrt/fxcrt_windows.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
-#ifndef _FXCRT_WINDOWS_
-#define _FXCRT_WINDOWS_
+#ifndef FXCRT_WINDOWS_H_
+#define FXCRT_WINDOWS_H_
+
 #include "extension.h"
+
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 class CFXCRT_FileAccess_Win64 : public IFXCRT_FileAccess
 {
 public:
     CFXCRT_FileAccess_Win64();
     virtual ~CFXCRT_FileAccess_Win64();
     virtual FX_BOOL             Open(FX_BSTR fileName, FX_DWORD dwMode);
     virtual FX_BOOL             Open(FX_WSTR fileName, FX_DWORD dwMode);
     virtual void                Close();
     virtual void                Release();
     virtual FX_FILESIZE GetSize() const;
     virtual FX_FILESIZE GetPosition() const;
     virtual FX_FILESIZE SetPosition(FX_FILESIZE pos);
     virtual size_t              Read(void* pBuffer, size_t szBuffer);
     virtual size_t              Write(const void* pBuffer, size_t szBuffer);
     virtual size_t              ReadPos(void* pBuffer, size_t szBuffer, FX_FILESIZE pos);
     virtual size_t              WritePos(const void* pBuffer, size_t szBuffer, FX_FILESIZE pos);
     virtual FX_BOOL             Flush();
     virtual FX_BOOL             Truncate(FX_FILESIZE szFile);
 protected:
     FX_LPVOID   m_hFile;
 };
 #endif
-#endif
+
+#endif  // FXCRT_WINDOWS_H_