Fix missing or broken include guard macros in pdfium headers.

core/include/fpdfdoc/fpdf_ap.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 _FPDF_AP_H_
 #define _FPDF_AP_H_
+
 #include "../fxcrt/fx_basic.h"
 #include "../fpdfapi/fpdf_parser.h"
 #include "fpdf_vt.h"
 class IPVT_FontMap
 {
 public:
 
     virtual CPDF_Font*                                          GetPDFFont(FX_INT32 nFontIndex) = 0;
 
     virtual CFX_ByteString                                      GetPDFFontAlias(FX_INT32 nFontIndex) = 0;
@@ skipping 65 matching lines @@
 
     static CFX_ByteString                                       GenerateEditAP(IPVT_FontMap * pFontMap, IPDF_VariableText_Iterator * pIterator,
             const CPDF_Point & ptOffset, FX_BOOL bContinuous, FX_WORD SubWord = 0, const CPVT_WordRange * pVisible = NULL);
 
     static CFX_ByteString                                       GenerateBorderAP(const CPDF_Rect & rect, FX_FLOAT fWidth,
             const CPVT_Color & color, const CPVT_Color & crLeftTop, const CPVT_Color & crRightBottom,
             FX_INT32 nStyle, const CPVT_Dash & dash);
 
     static CFX_ByteString                                       GenerateColorAP(const CPVT_Color & color, const FX_BOOL & bFillOrStroke);
 };
+
+#endif  // _FPDF_AP_H_