Remove the GetCaption dataprovider method

xfa/fwl/core/cfwl_checkbox.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_CORE_CFWL_CHECKBOX_H_
 #define XFA_FWL_CORE_CFWL_CHECKBOX_H_
 
 #include "xfa/fwl/core/cfwl_widget.h"
 #include "xfa/fwl/core/ifwl_checkbox.h"
 
 class CFWL_CheckBox : public CFWL_Widget, public IFWL_CheckBox::DataProvider {
  public:
   explicit CFWL_CheckBox(const IFWL_App* pApp);
   ~CFWL_CheckBox() override;
 
   void Initialize();
 
-  // IFWL_Widget::DataProvider
-  void GetCaption(IFWL_Widget* pWidget, CFX_WideString& wsCaption) override;
-
   // IFWL_CheckBox::DataProvider
   FX_FLOAT GetBoxSize(IFWL_Widget* pWidget) override;
 
   void SetBoxSize(FX_FLOAT fHeight);
 
  private:
   FX_FLOAT m_fBoxHeight;
 };
 
 #endif  // XFA_FWL_CORE_CFWL_CHECKBOX_H_