Cleanup CPDFXFA_Page.

fpdfsdk/fpdfxfa/include/fpdfxfa_page.h

 // Copyright 2014 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 FPDFSDK_FPDFXFA_INCLUDE_FPDFXFA_PAGE_H_
 #define FPDFSDK_FPDFXFA_INCLUDE_FPDFXFA_PAGE_H_
 
+#include <memory>
+
 #include "core/fpdfapi/fpdf_parser/include/cpdf_dictionary.h"
 #include "core/fpdfapi/include/cpdf_modulemgr.h"
 #include "core/fxcrt/include/fx_coordinates.h"
 #include "core/fxcrt/include/fx_system.h"
 
 class CPDFXFA_Document;
 class CPDF_Page;
 class CXFA_FFPageView;
 
 class CPDFXFA_Page {
  public:
   CPDFXFA_Page(CPDFXFA_Document* pDoc, int page_index);
-  ~CPDFXFA_Page();
 
+  void AddRef() { m_iRef++; }
   void Release();
-  void AddRef() { m_iRef++; }
+
   FX_BOOL LoadPage();
   FX_BOOL LoadPDFPage(CPDF_Dictionary* pageDict);
-  CPDFXFA_Document* GetDocument() { return m_pDocument; }
-  int GetPageIndex() { return m_iPageIndex; }
-  CPDF_Page* GetPDFPage() { return m_pPDFPage; }
-  CXFA_FFPageView* GetXFAPageView() { return m_pXFAPageView; }
+  CPDFXFA_Document* GetDocument() const { return m_pDocument; }
+  int GetPageIndex() const { return m_iPageIndex; }
+  CPDF_Page* GetPDFPage() const { return m_pPDFPage.get(); }
+  CXFA_FFPageView* GetXFAPageView() const { return m_pXFAPageView; }
+
   void SetXFAPageView(CXFA_FFPageView* pPageView) {
     m_pXFAPageView = pPageView;
   }
 
-  FX_FLOAT GetPageWidth();
-  FX_FLOAT GetPageHeight();
+  FX_FLOAT GetPageWidth() const;
+  FX_FLOAT GetPageHeight() const;
 
   void DeviceToPage(int start_x,
                     int start_y,
                     int size_x,
                     int size_y,
                     int rotate,
                     int device_x,
                     int device_y,
                     double* page_x,
                     double* page_y);
   void PageToDevice(int start_x,
                     int start_y,
                     int size_x,
                     int size_y,
                     int rotate,
                     double page_x,
                     double page_y,
                     int* device_x,
                     int* device_y);
 
   void GetDisplayMatrix(CFX_Matrix& matrix,
                         int xPos,
                         int yPos,
                         int xSize,
                         int ySize,
                         int iRotate) const;
 
  protected:
+  // Refcounted class.
+  ~CPDFXFA_Page();
+
   FX_BOOL LoadPDFPage();
   FX_BOOL LoadXFAPageView();
 
  private:
-  CPDF_Page* m_pPDFPage;
+  std::unique_ptr<CPDF_Page> m_pPDFPage;
   CXFA_FFPageView* m_pXFAPageView;
-  int m_iPageIndex;
-  CPDFXFA_Document* m_pDocument;
+  CPDFXFA_Document* const m_pDocument;
+  const int m_iPageIndex;
   int m_iRef;
 };
 
 #endif  // FPDFSDK_FPDFXFA_INCLUDE_FPDFXFA_PAGE_H_