Re-land "Make CPDF_IndirectObjectHolder use unique_ptr to objects""

core/fpdfapi/fpdf_parser/include/cpdf_indirect_object_holder.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_CPDF_INDIRECT_OBJECT_HOLDER_H_
 #define CORE_FPDFAPI_FPDF_PARSER_INCLUDE_CPDF_INDIRECT_OBJECT_HOLDER_H_
 
 #include <map>
+#include <memory>
 
 #include "core/fxcrt/include/fx_system.h"
 
 class CPDF_Object;
 
 class CPDF_IndirectObjectHolder {
  public:
-  using iterator = std::map<uint32_t, CPDF_Object*>::iterator;
-  using const_iterator = std::map<uint32_t, CPDF_Object*>::const_iterator;
+  using const_iterator =
+      std::map<uint32_t, std::unique_ptr<CPDF_Object>>::const_iterator;
 
   CPDF_IndirectObjectHolder();
   virtual ~CPDF_IndirectObjectHolder();
 
   CPDF_Object* GetIndirectObject(uint32_t objnum) const;
   CPDF_Object* GetOrParseIndirectObject(uint32_t objnum);
   void ReleaseIndirectObject(uint32_t objnum);
 
   // Take ownership of |pObj|.
   uint32_t AddIndirectObject(CPDF_Object* pObj);
   bool ReplaceIndirectObjectIfHigherGeneration(uint32_t objnum,
                                                CPDF_Object* pObj);
 
   uint32_t GetLastObjNum() const { return m_LastObjNum; }
   void SetLastObjNum(uint32_t objnum) { m_LastObjNum = objnum; }
 
-  iterator begin() { return m_IndirectObjs.begin(); }
   const_iterator begin() const { return m_IndirectObjs.begin(); }
-  iterator end() { return m_IndirectObjs.end(); }
   const_iterator end() const { return m_IndirectObjs.end(); }
 
  protected:
   virtual CPDF_Object* ParseIndirectObject(uint32_t objnum);
 
  private:
   uint32_t m_LastObjNum;
-  std::map<uint32_t, CPDF_Object*> m_IndirectObjs;
+  std::map<uint32_t, std::unique_ptr<CPDF_Object>> m_IndirectObjs;
 };
 
 #endif  // CORE_FPDFAPI_FPDF_PARSER_INCLUDE_CPDF_INDIRECT_OBJECT_HOLDER_H_