Use virtual function to retrieve interface pointer

xfa/fwl/lightwidget/cfwl_combobox.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 XFA_FWL_LIGHTWIDGET_CFWL_COMBOBOX_H_
 #define XFA_FWL_LIGHTWIDGET_CFWL_COMBOBOX_H_
 
 #include <memory>
 #include <vector>
 
 #include "xfa/fwl/basewidget/ifwl_combobox.h"
 #include "xfa/fwl/lightwidget/cfwl_widget.h"
 
 class CFWL_WidgetProperties;
 class IFWL_ComboBoxDP;
 class CFWL_ComboBoxDP;
 class CFWL_ComboBoxItem;
 
 class CFWL_ComboBox : public CFWL_Widget {
  public:
   CFWL_ComboBox();
   ~CFWL_ComboBox() override;
 
+  IFWL_ComboBox* GetWidget() override;
+  const IFWL_ComboBox* GetWidget() const override;
+
   static CFWL_ComboBox* Create();
   FWL_Error Initialize(const CFWL_WidgetProperties* pProperties = nullptr);
   int32_t AddString(const CFX_WideStringC& wsText);
   int32_t AddString(const CFX_WideStringC& wsText, CFX_DIBitmap* pIcon);
   bool RemoveAt(int32_t iIndex);  // Returns false iff |iIndex| out of range.
   void RemoveAll();
   int32_t CountItems();
   FWL_Error GetTextByIndex(int32_t iIndex, CFX_WideString& wsText);
   int32_t GetCurSel();
   FWL_Error SetCurSel(int32_t iSel);
@@ skipping 101 matching lines @@
   CFX_RectF m_rtItem;
   uint32_t m_dwStyles;
   CFX_WideString m_wsText;
   CFX_DIBitmap* m_pDIB;
   uint32_t m_dwCheckState;
   CFX_RectF m_rtCheckBox;
   void* m_pData;
 };
 
 #endif  // XFA_FWL_LIGHTWIDGET_CFWL_COMBOBOX_H_