Use override in more classes in core/

core/include/fxge/fpf.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 CORE_INCLUDE_FXGE_FPF_H_
 #define CORE_INCLUDE_FXGE_FPF_H_
 
 #include "../fxcrt/fx_coordinates.h"
 
-class IFPF_DeviceModule;
 class IFPF_FontMgr;
-class IFPF_Font;
+
 class IFPF_DeviceModule {
  public:
   virtual ~IFPF_DeviceModule() {}
   virtual void Destroy() = 0;
   virtual IFPF_FontMgr* GetFontMgr() = 0;
 };
+
 IFPF_DeviceModule* FPF_GetDeviceModule();
+
 #define FPF_MATCHFONT_REPLACEANSI 1
+
 typedef struct FPF_HFONT_ { void* pData; } * FPF_HFONT;
+
 class IFPF_Font {
  public:
   virtual void Release() = 0;
   virtual IFPF_Font* Retain() = 0;
   virtual FPF_HFONT GetHandle() = 0;
   virtual CFX_ByteString GetFamilyName() = 0;
   virtual CFX_WideString GetPsName() = 0;
   virtual FX_DWORD GetFontStyle() const = 0;
   virtual uint8_t GetCharset() const = 0;
 
   virtual int32_t GetGlyphIndex(FX_WCHAR wUnicode) = 0;
   virtual int32_t GetGlyphWidth(int32_t iGlyphIndex) = 0;
 
   virtual int32_t GetAscent() const = 0;
   virtual int32_t GetDescent() const = 0;
 
   virtual FX_BOOL GetGlyphBBox(int32_t iGlyphIndex, FX_RECT& rtBBox) = 0;
   virtual FX_BOOL GetBBox(FX_RECT& rtBBox) = 0;
 
   virtual int32_t GetHeight() const = 0;
   virtual int32_t GetItalicAngle() const = 0;
   virtual FX_DWORD GetFontData(FX_DWORD dwTable,
                                uint8_t* pBuffer,
                                FX_DWORD dwSize) = 0;
 
  protected:
-  ~IFPF_Font() {}
+  virtual ~IFPF_Font() {}
 };
+
 class IFPF_FontMgr {
  public:
   virtual ~IFPF_FontMgr() {}
   virtual void LoadSystemFonts() = 0;
   virtual void LoadPrivateFont(IFX_FileRead* pFontFile) = 0;
   virtual void LoadPrivateFont(const CFX_ByteStringC& bsFileName) = 0;
   virtual void LoadPrivateFont(void* pBuffer, size_t szBuffer) = 0;
 
   virtual IFPF_Font* CreateFont(const CFX_ByteStringC& bsFamilyname,
                                 uint8_t charset,
                                 FX_DWORD dwStyle,
                                 FX_DWORD dwMatch = 0) = 0;
 };
 
 #endif  // CORE_INCLUDE_FXGE_FPF_H_