Return unique_ptr from CPDF_Object::Clone().

core/fpdfapi/parser/cpdf_string.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_PARSER_CPDF_STRING_H_
 #define CORE_FPDFAPI_PARSER_CPDF_STRING_H_
 
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
 
 class CPDF_String : public CPDF_Object {
  public:
   CPDF_String();
   CPDF_String(const CFX_ByteString& str, bool bHex);
   explicit CPDF_String(const CFX_WideString& str);
   ~CPDF_String() override;
 
-  // CPDF_Object.
+  // CPDF_Object:
   Type GetType() const override;
-  CPDF_Object* Clone() const override;
+  std::unique_ptr<CPDF_Object> Clone() const override;
   CFX_ByteString GetString() const override;
   CFX_WideString GetUnicodeText() const override;
   void SetString(const CFX_ByteString& str) override;
   bool IsString() const override;
   CPDF_String* AsString() override;
   const CPDF_String* AsString() const override;
 
   bool IsHex() const { return m_bHex; }
 
  protected:
   CFX_ByteString m_String;
   bool m_bHex;
 };
 
 inline CPDF_String* ToString(CPDF_Object* obj) {
   return obj ? obj->AsString() : nullptr;
 }
 
 inline const CPDF_String* ToString(const CPDF_Object* obj) {
   return obj ? obj->AsString() : nullptr;
 }
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_STRING_H_