Make code compile with clang_use_chrome_plugin (part VI)

xfa/fwl/lightwidget/cfwl_scrollbar.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_SCROLLBAR_H_
 #define XFA_FWL_LIGHTWIDGET_CFWL_SCROLLBAR_H_
 
 #include "xfa/fwl/lightwidget/cfwl_widget.h"
 
 class CFWL_ScrollBar : public CFWL_Widget {
  public:
+  CFWL_ScrollBar();
+  ~CFWL_ScrollBar() override;
+
   static CFWL_ScrollBar* Create();
+
   FWL_Error Initialize(const CFWL_WidgetProperties* pProperties = NULL);
   FX_BOOL IsVertical();
   FWL_Error GetRange(FX_FLOAT& fMin, FX_FLOAT& fMax);
   FWL_Error SetRange(FX_FLOAT fMin, FX_FLOAT fMax);
   FX_FLOAT GetPageSize();
   FWL_Error SetPageSize(FX_FLOAT fPageSize);
   FX_FLOAT GetStepSize();
   FWL_Error SetStepSize(FX_FLOAT fStepSize);
   FX_FLOAT GetPos();
   FWL_Error SetPos(FX_FLOAT fPos);
   FX_FLOAT GetTrackPos();
   FWL_Error SetTrackPos(FX_FLOAT fTrackPos);
   FX_BOOL DoScroll(uint32_t dwCode, FX_FLOAT fPos = 0.0f);
-  CFWL_ScrollBar();
-  virtual ~CFWL_ScrollBar();
 };
 
 #endif  // XFA_FWL_LIGHTWIDGET_CFWL_SCROLLBAR_H_