Use more unique_ptrs in CPDF_Image.

core/fpdfapi/page/cpdf_pageobject.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_PAGE_CPDF_PAGEOBJECT_H_
 #define CORE_FPDFAPI_PAGE_CPDF_PAGEOBJECT_H_
 
 #include "core/fpdfapi/page/cpdf_contentmark.h"
@@ skipping 13 matching lines @@
     TEXT = 1,
     PATH,
     IMAGE,
     SHADING,
     FORM,
   };
 
   CPDF_PageObject();
   ~CPDF_PageObject() override;
 
-  virtual CPDF_PageObject* Clone() const = 0;
   virtual Type GetType() const = 0;
   virtual void Transform(const CFX_Matrix& matrix) = 0;
   virtual bool IsText() const;
   virtual bool IsPath() const;
   virtual bool IsImage() const;
   virtual bool IsShading() const;
   virtual bool IsForm() const;
   virtual CPDF_TextObject* AsText();
   virtual const CPDF_TextObject* AsText() const;
   virtual CPDF_PathObject* AsPath();
@@ skipping 17 matching lines @@
 
  protected:
   void CopyData(const CPDF_PageObject* pSrcObject);
 
  private:
   CPDF_PageObject(const CPDF_PageObject& src) = delete;
   void operator=(const CPDF_PageObject& src) = delete;
 };
 
 #endif  // CORE_FPDFAPI_PAGE_CPDF_PAGEOBJECT_H_