Use override in more classes in core/

core/src/fpdfapi/fpdf_render/fpdf_render_image.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/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_pageobj.h"
 #include "../../../include/fpdfapi/fpdf_render.h"
 #include "../../../include/fxcodec/fx_codec.h"
@@ skipping 121 matching lines @@
   return FXSYS_RGB(m_Samples[FXSYS_GetRValue(rgb)],
                    m_Samples[256 + FXSYS_GetGValue(rgb)],
                    m_Samples[512 + FXSYS_GetBValue(rgb)]);
 }
 CFX_DIBSource* CPDF_TransferFunc::TranslateImage(const CFX_DIBSource* pSrc,
                                                  FX_BOOL bAutoDropSrc) {
   CPDF_DIBTransferFunc* pDest = new CPDF_DIBTransferFunc(this);
   pDest->LoadSrc(pSrc, bAutoDropSrc);
   return pDest;
 }
+
+CPDF_DIBTransferFunc::~CPDF_DIBTransferFunc() {
+}
+
 FXDIB_Format CPDF_DIBTransferFunc::GetDestFormat() {
   if (m_pSrc->IsAlphaMask()) {
     return FXDIB_8bppMask;
   }
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
   return (m_pSrc->HasAlpha()) ? FXDIB_Argb : FXDIB_Rgb32;
 #else
   return (m_pSrc->HasAlpha()) ? FXDIB_Argb : FXDIB_Rgb;
 #endif
 }
@@ skipping 1011 matching lines @@
     for (int i = 0; i < size; i++) {
       dest_buf[i] = pTransfer[src_buf[i]];
     }
   } else {
     FXSYS_memcpy(dest_buf, src_buf, dest_pitch * height);
   }
   delete pFunc;
   FX_Free(pTransfer);
   return pMask;
 }