Fix ALL the include guards.

core/include/fxcrt/fx_memory.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 _FX_MEMORY_H_
-#define _FX_MEMORY_H_
+#ifndef FX_MEMORY_H_
+#define FX_MEMORY_H_
 
 #include "fx_system.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 // For external C libraries to malloc through PDFium. These may return NULL.
 void*   FXMEM_DefaultAlloc(size_t byte_size, int flags);
 void*   FXMEM_DefaultRealloc(void* pointer, size_t new_size, int flags);
 void    FXMEM_DefaultFree(void* pointer, int flags);
@@ skipping 89 matching lines @@
 
     void        Free(void*) {}
 
     void        FreeAll();
 private:
 
     size_t      m_TrunkSize;
 
     void*       m_pFirstTrunk;
 };
-#endif  // __cplusplust
-#endif  // _FX_MEMORY_H_
+#endif  // __cplusplus
+
+#endif  // FX_MEMORY_H_