Fix ALL the include guards.

core/include/fxcrt/fx_xml.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_XML_H_
-#define _FX_XML_H_
+#ifndef FX_XML_H_
+#define FX_XML_H_
 
 #include "fx_basic.h"
 
 class CXML_AttrItem 
 {
 public:
     CFX_ByteString      m_QSpaceName;
     CFX_ByteString      m_AttrName;
     CFX_WideString      m_Value;
 };
@@ skipping 150 matching lines @@
     CXML_Element*                       m_pParent;
     CFX_ByteString                      m_QSpaceName;
     CFX_ByteString                      m_TagName;
 
     CXML_AttrMap                        m_AttrMap;
 
     CFX_PtrArray                        m_Children;
     friend class CXML_Parser;
     friend class CXML_Composer;
 };
-#endif
+
+#endif  // FX_XML_H_