Remove the GetCaption dataprovider method

xfa/fwl/core/cfwl_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/cfwl_datetimepicker.h"
 
 #include <memory>
 
@@ skipping 39 matching lines @@
 void CFWL_DateTimePicker::SetEditText(const CFX_WideString& wsText) {
   ToDateTimePicker(GetWidget())->SetEditText(wsText);
 }
 
 void CFWL_DateTimePicker::SetCurSel(int32_t iYear,
                                     int32_t iMonth,
                                     int32_t iDay) {
   ToDateTimePicker(GetWidget())->SetCurSel(iYear, iMonth, iDay);
 }
 
-void CFWL_DateTimePicker::GetCaption(IFWL_Widget* pWidget,
-                                     CFX_WideString& wsCaption) {
-  wsCaption = L"";
-}
-
 void CFWL_DateTimePicker::GetToday(IFWL_Widget* pWidget,
                                    int32_t& iYear,
                                    int32_t& iMonth,
                                    int32_t& iDay) {
   iYear = 2011;
   iMonth = 1;
   iDay = 1;
 }
 
 void CFWL_DateTimePicker::GetBBox(CFX_RectF& rect) {
   ToDateTimePicker(GetWidget())->GetBBox(rect);
 }
 
 void CFWL_DateTimePicker::SetEditLimit(int32_t nLimit) {
   ToDateTimePicker(GetWidget())->SetEditLimit(nLimit);
 }
 
 void CFWL_DateTimePicker::ModifyEditStylesEx(uint32_t dwStylesExAdded,
                                              uint32_t dwStylesExRemoved) {
   ToDateTimePicker(GetWidget())
       ->ModifyEditStylesEx(dwStylesExAdded, dwStylesExRemoved);
 }