Use override in more classes in fpdfsdk/

fpdfsdk/src/fpdfsave.cpp

 // 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
 
 #include "../../public/fpdf_edit.h"
 #include "../../public/fpdf_save.h"
 #include "../include/fsdk_define.h"
 
 #if _FX_OS_ == _FX_ANDROID_
 #include "time.h"
 #else
 #include <ctime>
 #endif
 
 class CFX_IFileWrite final : public IFX_StreamWrite {
  public:
   CFX_IFileWrite();
   FX_BOOL Init(FPDF_FILEWRITE* pFileWriteStruct);
-  virtual FX_BOOL WriteBlock(const void* pData, size_t size) override;
-  virtual void Release() override {}
+  FX_BOOL WriteBlock(const void* pData, size_t size) override;
+  void Release() override;
 
  protected:
+  ~CFX_IFileWrite() override {}
+
   FPDF_FILEWRITE* m_pFileWriteStruct;
 };
 
 CFX_IFileWrite::CFX_IFileWrite() {
   m_pFileWriteStruct = NULL;
 }
 
 FX_BOOL CFX_IFileWrite::Init(FPDF_FILEWRITE* pFileWriteStruct) {
   if (!pFileWriteStruct)
     return FALSE;
 
   m_pFileWriteStruct = pFileWriteStruct;
   return TRUE;
 }
 
 FX_BOOL CFX_IFileWrite::WriteBlock(const void* pData, size_t size) {
   if (!m_pFileWriteStruct)
     return FALSE;
 
   m_pFileWriteStruct->WriteBlock(m_pFileWriteStruct, pData, size);
   return TRUE;
 }
 
+void CFX_IFileWrite::Release() {
+  delete this;
+}
+
 FPDF_BOOL _FPDF_Doc_Save(FPDF_DOCUMENT document,
                          FPDF_FILEWRITE* pFileWrite,
                          FPDF_DWORD flags,
                          FPDF_BOOL bSetVersion,
                          int fileVerion) {
   CPDF_Document* pDoc = (CPDF_Document*)document;
   if (!pDoc)
     return 0;
 
   if (flags < FPDF_INCREMENTAL || flags > FPDF_REMOVE_SECURITY) {
     flags = 0;
   }
 
   CPDF_Creator FileMaker(pDoc);
   if (bSetVersion)
     FileMaker.SetFileVersion(fileVerion);
   if (flags == FPDF_REMOVE_SECURITY) {
     flags = 0;
     FileMaker.RemoveSecurity();
   }
   CFX_IFileWrite* pStreamWrite = NULL;
   FX_BOOL bRet;
   pStreamWrite = new CFX_IFileWrite;
   pStreamWrite->Init(pFileWrite);
   bRet = FileMaker.Create(pStreamWrite, flags);
-  delete pStreamWrite;
+  pStreamWrite->Release();
   return bRet;
 }
 
 DLLEXPORT FPDF_BOOL STDCALL FPDF_SaveAsCopy(FPDF_DOCUMENT document,
                                             FPDF_FILEWRITE* pFileWrite,
                                             FPDF_DWORD flags) {
   return _FPDF_Doc_Save(document, pFileWrite, flags, FALSE, 0);
 }
 
 DLLEXPORT FPDF_BOOL STDCALL FPDF_SaveWithVersion(FPDF_DOCUMENT document,
                                                  FPDF_FILEWRITE* pFileWrite,
                                                  FPDF_DWORD flags,
                                                  int fileVersion) {
   return _FPDF_Doc_Save(document, pFileWrite, flags, TRUE, fileVersion);
 }