Add FX_OVERRIDE and use it for virtual functions of FX_FINAL classes.

fpdfsdk/include/fsdk_define.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_DEFINE_H
 #define _FPDFSDK_DEFINE_H
 
 #ifdef _WIN32
@@ skipping 89 matching lines @@
 typedef unsigned int FX_UINT;   
 
 #include "fpdfview.h"
 
 class CPDF_CustomAccess FX_FINAL : public IFX_FileRead, public CFX_Object
 {
 public:
         CPDF_CustomAccess(FPDF_FILEACCESS* pFileAccess);
         ~CPDF_CustomAccess() {}
 
-        virtual CFX_ByteString GetFullPath() { return ""; }
-        virtual FX_FILESIZE     GetSize() { return m_FileAccess.m_FileLen; }
+        virtual FX_FILESIZE     GetSize() FX_OVERRIDE { return m_FileAccess.m_FileLen; }
 
-        virtual FX_BOOL         GetByte(FX_DWORD pos, FX_BYTE& ch);
-        virtual FX_BOOL         GetBlock(FX_DWORD pos, FX_LPBYTE pBuf, FX_DWORD size);
-        virtual void            Release() { delete this; }
+        virtual void            Release() FX_OVERRIDE { delete this; }
 
-        virtual FX_BOOL         ReadBlock(void* buffer, FX_FILESIZE offset, size_t size);
+        virtual FX_BOOL         ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) FX_OVERRIDE;
 
+private:
         FPDF_FILEACCESS         m_FileAccess;
-        FX_BYTE                         m_Buffer[512];
-        FX_DWORD                        m_BufferOffset;
 };
 
 void            FSDK_SetSandBoxPolicy(FPDF_DWORD policy, FPDF_BOOL enable);
 FPDF_BOOL       FSDK_IsSandBoxPolicyEnabled(FPDF_DWORD policy);
 
 
 #endif//_FPDFSDK_DEFINE_H