Use override in more classes in fpdfsdk/

fpdfsdk/include/pdfwindow/PWL_Icon.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_INCLUDE_PDFWINDOW_PWL_ICON_H_
 #define FPDFSDK_INCLUDE_PDFWINDOW_PWL_ICON_H_
 
 #include "../../../core/include/fxcrt/fx_string.h"
 #include "PWL_Wnd.h"
 
 class CPWL_Image : public CPWL_Wnd {
  public:
   CPWL_Image();
-  virtual ~CPWL_Image();
+  ~CPWL_Image() override;
 
   virtual CFX_ByteString GetImageAppStream();
 
   virtual void GetScale(FX_FLOAT& fHScale, FX_FLOAT& fVScale);
   virtual void GetImageOffset(FX_FLOAT& x, FX_FLOAT& y);
   virtual CPDF_Stream* GetPDFStream();
 
  public:
   void SetPDFStream(CPDF_Stream* pStream);
   void GetImageSize(FX_FLOAT& fWidth, FX_FLOAT& fHeight);
   CPDF_Matrix GetImageMatrix();
   CFX_ByteString GetImageAlias();
   void SetImageAlias(const FX_CHAR* sImageAlias);
 
  protected:
   CPDF_Stream* m_pPDFStream;
   CFX_ByteString m_sImageAlias;
 };
 
 class CPWL_Icon : public CPWL_Image {
  public:
   CPWL_Icon();
-  virtual ~CPWL_Icon();
+  ~CPWL_Icon() override;
 
   virtual CPDF_IconFit* GetIconFit() { return m_pIconFit; };
 
-  virtual void GetScale(FX_FLOAT& fHScale, FX_FLOAT& fVScale);
-  virtual void GetImageOffset(FX_FLOAT& x, FX_FLOAT& y);
+  // CPWL_Image
+  void GetScale(FX_FLOAT& fHScale, FX_FLOAT& fVScale) override;
+  void GetImageOffset(FX_FLOAT& x, FX_FLOAT& y) override;
 
   int32_t GetScaleMethod();
   FX_BOOL IsProportionalScale();
   void GetIconPosition(FX_FLOAT& fLeft, FX_FLOAT& fBottom);
   FX_BOOL GetFittingBounds();
 
   void SetIconFit(CPDF_IconFit* pIconFit) { m_pIconFit = pIconFit; };
 
  private:
   CPDF_IconFit* m_pIconFit;
 };
 
 #endif  // FPDFSDK_INCLUDE_PDFWINDOW_PWL_ICON_H_