Change IFWL_Widget to store a single delegate.

xfa/fwl/core/ifwl_datetimecalendar.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_datetimecalendar.h"
 
 #include "third_party/base/ptr_util.h"
 #include "xfa/fwl/core/cfwl_widgetmgr.h"
@@ skipping 13 matching lines @@
     : CFWL_MonthCalendarImpDelegate(pOwner), m_pOwner(pOwner) {
   m_bFlag = FALSE;
 }
 
 void CFWL_DateTimeCalendarImpDelegate::OnProcessMessage(
     CFWL_Message* pMessage) {
   CFWL_MessageType dwCode = pMessage->GetClassID();
   if (dwCode == CFWL_MessageType::SetFocus ||
       dwCode == CFWL_MessageType::KillFocus) {
     IFWL_Widget* pOuter = m_pOwner->GetOuter();
-    pOuter->GetCurrentDelegate()->OnProcessMessage(pMessage);
+    pOuter->GetDelegate()->OnProcessMessage(pMessage);
     return;
   }
   if (dwCode == CFWL_MessageType::Mouse) {
     CFWL_MsgMouse* pMsg = static_cast<CFWL_MsgMouse*>(pMessage);
     if (pMsg->m_dwCmd == FWL_MouseCommand::LeftButtonDown)
       OnLButtonDownEx(pMsg);
     else if (pMsg->m_dwCmd == FWL_MouseCommand::LeftButtonUp)
       OnLButtonUpEx(pMsg);
     return;
   }
@@ skipping 150 matching lines @@
       rtInvalidate.Union(lpDatesInfo->rect);
     }
     m_pOwner->AddSelDay(iCurSel);
     IFWL_DateTimePicker* pDateTime =
         static_cast<IFWL_DateTimePicker*>(m_pOwner->m_pOuter);
     pDateTime->ProcessSelChanged(m_pOwner->m_iCurYear, m_pOwner->m_iCurMonth,
                                  iCurSel);
     pDateTime->ShowMonthCalendar(FALSE);
   }
 }