Move CPDF_Reference::SafeGetDirect() out of the header.

core/fpdfapi/fpdf_parser/cpdf_reference.cpp

 // 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
 
 #include "core/fpdfapi/fpdf_parser/cpdf_reference.h"
 
 #include "core/fpdfapi/fpdf_parser/cpdf_indirect_object_holder.h"
 #include "third_party/base/stl_util.h"
@@ skipping 49 matching lines @@
   pVisited->insert(this);
   if (bDirect) {
     auto* pDirect = GetDirect();
     return pDirect && !pdfium::ContainsKey(*pVisited, pDirect)
                ? pDirect->CloneNonCyclic(true, pVisited)
                : nullptr;
   }
   return new CPDF_Reference(m_pObjList, m_RefObjNum);
 }
 
+CPDF_Object* CPDF_Reference::SafeGetDirect() const {
+  CPDF_Object* obj = GetDirect();
+  return (obj && !obj->IsReference()) ? obj : nullptr;
+}
+
 void CPDF_Reference::SetRef(CPDF_IndirectObjectHolder* pDoc, uint32_t objnum) {
   m_pObjList = pDoc;
   m_RefObjNum = objnum;
 }
 
 CPDF_Object* CPDF_Reference::GetDirect() const {
   return m_pObjList ? m_pObjList->GetOrParseIndirectObject(m_RefObjNum)
                     : nullptr;
 }