Fix remaining -Wdelete-non-virtual-dtor violations on Windows.

core/src/fxge/win32/fx_win32_gdipext.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 "../../../include/fxge/fx_ge.h"
 #if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN64_
 #include <windows.h>
 #include <gdiplus.h>
@@ skipping 985 matching lines @@
     }
     if (pMatrix) {
         CallFunc(GdipDeleteMatrix)(pMatrix);
     }
     FX_Free(points);
     FX_Free(types);
     CallFunc(GdipDeletePath)(pGpPath);
     CallFunc(GdipDeleteGraphics)(pGraphics);
     return TRUE;
 }
-class GpStream : public IStream, public CFX_Object
+class GpStream FX_FINAL : public IStream, public CFX_Object
 {
     LONG        m_RefCount;
     int     m_ReadPos;
     CFX_ByteTextBuf     m_InterStream;
 public:
     GpStream()
     {
         m_RefCount = 1;
         m_ReadPos = 0;
     }
@@ skipping 259 matching lines @@
         FXSYS_memcpy32(pData, pInfo->pScan0, dest_pitch * height);
     } else for (int i = 0; i < height; i ++) {
             FXSYS_memcpy32(pData + dest_pitch * i, pInfo->pScan0 + pInfo->Stride * i, dest_pitch);
         }
     CFX_DIBitmap* pDIBitmap = _FX_WindowsDIB_LoadFromBuf(pInfo->pbmi, pData, pInfo->pbmi->bmiHeader.biBitCount == 32);
     FX_Free(pData);
     FreeDIBitmap(pInfo);
     return pDIBitmap;
 }
 #endif