Use more unique_ptrs in CPDF_Image.

core/fpdfapi/page/cpdf_form.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/page/cpdf_form.h"
 
 #include "core/fpdfapi/page/cpdf_pageobject.h"
 #include "core/fpdfapi/page/cpdf_pageobjectholder.h"
@@ skipping 32 matching lines @@
   m_ParseState = CONTENT_PARSING;
 }
 
 void CPDF_Form::ParseContent(CPDF_AllStates* pGraphicStates,
                              const CFX_Matrix* pParentMatrix,
                              CPDF_Type3Char* pType3Char,
                              int level) {
   StartParse(pGraphicStates, pParentMatrix, pType3Char, level);
   ContinueParse(nullptr);
 }
-
-CPDF_Form* CPDF_Form::Clone() const {
-  CPDF_Form* pCloneForm =
-      new CPDF_Form(m_pDocument, m_pPageResources, m_pFormStream, m_pResources);
-  for (const auto& pObj : m_PageObjectList)
-    pCloneForm->m_PageObjectList.emplace_back(pObj->Clone());
-
-  return pCloneForm;
-}