Add fallback fonts in pdfium

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 <memory>
@@ skipping 70 matching lines @@
   FX_BOOL IsStandardFont() const;
   FXFT_Face GetFace() const { return m_Font.GetFace(); }
   void AppendChar(CFX_ByteString& str, uint32_t charcode) const;
 
   void GetFontBBox(FX_RECT& rect) const { rect = m_FontBBox; }
   int GetTypeAscent() const { return m_Ascent; }
   int GetTypeDescent() const { return m_Descent; }
   int GetItalicAngle() const { return m_ItalicAngle; }
   int GetStemV() const { return m_StemV; }
   int GetStringWidth(const FX_CHAR* pString, int size);
+  uint32_t FallbackFontFromCharcode(uint32_t charcode);
+  int FallbackGlyphFromCharcode(int fallbackFont, uint32_t charcode);
 
   virtual int GetCharWidthF(uint32_t charcode, int level = 0) = 0;
   virtual FX_RECT GetCharBBox(uint32_t charcode, int level = 0) = 0;
 
   CPDF_Document* m_pDocument;
   CFX_Font m_Font;
+  std::vector<std::unique_ptr<CFX_Font>> m_FontFallbacks;
 
  protected:
   CPDF_Font();
 
   virtual FX_BOOL Load() = 0;
 
   FX_BOOL Initialize();
   void LoadUnicodeMap() const;  // logically const only.
   void LoadPDFEncoding(CPDF_Object* pEncoding,
                        int& iBaseEncoding,
@@ skipping 14 matching lines @@
   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_