Avoid const-cast in CPDF_Font

core/fpdfapi/fpdf_font/include/cpdf_font.h

 // Copyright 2016 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 CORE_FPDFAPI_FPDF_FONT_INCLUDE_CPDF_FONT_H_
 #define CORE_FPDFAPI_FPDF_FONT_INCLUDE_CPDF_FONT_H_
 
 #include "core/fxcrt/include/fx_string.h"
@@ skipping 81 matching lines @@
 
   CPDF_Document* m_pDocument;
   CFX_Font m_Font;
 
  protected:
   CPDF_Font();
 
   virtual FX_BOOL Load() = 0;
 
   FX_BOOL Initialize();
-  void LoadUnicodeMap();
+  void LoadUnicodeMap() const;  // logically const only.
   void LoadPDFEncoding(CPDF_Object* pEncoding,
                        int& iBaseEncoding,
                        CFX_ByteString*& pCharNames,
                        FX_BOOL bEmbedded,
                        FX_BOOL bTrueType);
   void LoadFontDescriptor(CPDF_Dictionary* pDict);
   void CheckFontMetrics();
 
   const FX_CHAR* GetAdobeCharName(int iBaseEncoding,
                                   const CFX_ByteString* pCharNames,
                                   int charcode);
 
   CFX_ByteString m_BaseFont;
   CPDF_StreamAcc* m_pFontFile;
   CPDF_Dictionary* m_pFontDict;
-  CPDF_ToUnicodeMap* m_pToUnicodeMap;
-  FX_BOOL m_bToUnicodeLoaded;
+  mutable CPDF_ToUnicodeMap* m_pToUnicodeMap;
+  mutable FX_BOOL m_bToUnicodeLoaded;
   int m_Flags;
   FX_RECT m_FontBBox;
   int m_StemV;
   int m_Ascent;
   int m_Descent;
   int m_ItalicAngle;
 };
 
 #endif  // CORE_FPDFAPI_FPDF_FONT_INCLUDE_CPDF_FONT_H_