Use string pools in some dictionaries

core/fpdfapi/fpdf_parser/include/cfdf_document.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_PARSER_INCLUDE_CFDF_DOCUMENT_H_
 #define CORE_FPDFAPI_FPDF_PARSER_INCLUDE_CFDF_DOCUMENT_H_
 
 #include "core/fpdfapi/fpdf_parser/include/cpdf_indirect_object_holder.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_object.h"
+#include "core/fxcrt/include/cfx_string_pool_template.h"
 #include "core/fxcrt/include/fx_basic.h"
 
 class CPDF_Dictionary;
 
-class CFDF_Document : public CPDF_IndirectObjectHolder {
+class CFDF_Document : public CPDF_IndirectObjectHolder,
+                      public CFX_ByteStringPool {
  public:
   static CFDF_Document* CreateNewDoc();
   static CFDF_Document* ParseFile(IFX_FileRead* pFile,
                                   FX_BOOL bOwnFile = FALSE);
   static CFDF_Document* ParseMemory(const uint8_t* pData, uint32_t size);
   ~CFDF_Document() override;
 
   FX_BOOL WriteBuf(CFX_ByteTextBuf& buf) const;
   CPDF_Dictionary* GetRoot() const { return m_pRootDict; }
 
  protected:
   CFDF_Document();
   void ParseStream(IFX_FileRead* pFile, FX_BOOL bOwnFile);
 
   CPDF_Dictionary* m_pRootDict;
   IFX_FileRead* m_pFile;
   FX_BOOL m_bOwnFile;
 };
 
 #endif  // CORE_FPDFAPI_FPDF_PARSER_INCLUDE_CFDF_DOCUMENT_H_