Make CPDF_IndirectObjectHolder use unique_ptr to objects

core/fpdfapi/fpdf_parser/cfdf_document.cpp

 // 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
 
 #include "core/fpdfapi/fpdf_parser/include/cfdf_document.h"
 
 #include "core/fpdfapi/fpdf_edit/include/cpdf_creator.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_syntax_parser.h"
@@ skipping 72 matching lines @@
     }
   }
 }
 
 FX_BOOL CFDF_Document::WriteBuf(CFX_ByteTextBuf& buf) const {
   if (!m_pRootDict)
     return FALSE;
 
   buf << "%FDF-1.2\r\n";
   for (const auto& pair : *this)
-    buf << pair.first << " 0 obj\r\n" << pair.second << "\r\nendobj\r\n\r\n";
+    buf << pair.first << " 0 obj\r\n"
+        << pair.second.get() << "\r\nendobj\r\n\r\n";
 
   buf << "trailer\r\n<</Root " << m_pRootDict->GetObjNum()
       << " 0 R>>\r\n%%EOF\r\n";
   return TRUE;
 }