Return unique_ptr from CPDF_Object::Clone().

core/fpdfapi/parser/cpdf_boolean.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_BOOLEAN_H_
 #define CORE_FPDFAPI_PARSER_CPDF_BOOLEAN_H_
 
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
 
 class CPDF_Boolean : public CPDF_Object {
  public:
   CPDF_Boolean();
   explicit CPDF_Boolean(bool value);
   ~CPDF_Boolean() override;
 
   // CPDF_Object:
   Type GetType() const override;
-  CPDF_Object* Clone() const override;
+  std::unique_ptr<CPDF_Object> Clone() const override;
   CFX_ByteString GetString() const override;
   int GetInteger() const override;
   void SetString(const CFX_ByteString& str) override;
   bool IsBoolean() const override;
   CPDF_Boolean* AsBoolean() override;
   const CPDF_Boolean* AsBoolean() const override;
 
  protected:
   bool m_bValue;
 };
 
 inline CPDF_Boolean* ToBoolean(CPDF_Object* obj) {
   return obj ? obj->AsBoolean() : nullptr;
 }
 
 inline const CPDF_Boolean* ToBoolean(const CPDF_Object* obj) {
   return obj ? obj->AsBoolean() : nullptr;
 }
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_BOOLEAN_H_