Remove CPDF_Object::GetConstString and overrides

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/include/cpdf_reference.h"
 
 #include "core/fpdfapi/fpdf_parser/include/cpdf_indirect_object_holder.h"
 
 CPDF_Reference::CPDF_Reference(CPDF_IndirectObjectHolder* pDoc, int objnum)
     : m_pObjList(pDoc), m_RefObjNum(objnum) {}
 
 CPDF_Reference::~CPDF_Reference() {}
 
 CPDF_Object::Type CPDF_Reference::GetType() const {
   return REFERENCE;
 }
 
 CFX_ByteString CPDF_Reference::GetString() const {
   CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetString() : CFX_ByteString();
 }
 
-CFX_ByteStringC CPDF_Reference::GetConstString() const {
-  CPDF_Object* obj = SafeGetDirect();
-  return obj ? obj->GetConstString() : CFX_ByteStringC();
-}
-
 FX_FLOAT CPDF_Reference::GetNumber() const {
   CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetNumber() : 0;
 }
 
 int CPDF_Reference::GetInteger() const {
   CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetInteger() : 0;
 }
 
@@ skipping 23 matching lines @@
 }
 
 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->GetIndirectObject(m_RefObjNum) : nullptr;
 }