Remove the GetCaption dataprovider method

xfa/fwl/core/ifwl_datetimepicker.cpp

 // 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
 
 #include "xfa/fwl/core/ifwl_datetimepicker.h"
 
 #include <memory>
 #include <utility>
@@ skipping 657 matching lines @@
       ShowMonthCalendar(false);
     if (m_pEdit->GetStates() & FWL_WGTSTATE_Focused) {
       pMsg->m_pSrcTarget = m_pEdit.get();
       m_pEdit->GetDelegate()->OnProcessMessage(pMsg);
     }
   }
   rtInvalidate.Inflate(2, 2);
   Repaint(&rtInvalidate);
 }
 
-void IFWL_DateTimePicker::GetCaption(IFWL_Widget* pWidget,
-                                     CFX_WideString& wsCaption) {}
-
 int32_t IFWL_DateTimePicker::GetCurDay(IFWL_Widget* pWidget) {
   return m_iCurDay;
 }
 
 int32_t IFWL_DateTimePicker::GetCurMonth(IFWL_Widget* pWidget) {
   return m_iCurMonth;
 }
 
 int32_t IFWL_DateTimePicker::GetCurYear(IFWL_Widget* pWidget) {
   return m_iCurYear;
 }