Fold IFWL_DateTimeCalendar into IFWL_MonthCalendar

xfa/fwl/core/ifwl_datetimecalendar.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_IFWL_DATETIMECALENDAR_H_
-#define XFA_FWL_CORE_IFWL_DATETIMECALENDAR_H_
-
-#include "xfa/fwl/core/ifwl_monthcalendar.h"
-
-class IFWL_DateTimeCalendar : public IFWL_MonthCalendar {
- public:
-  IFWL_DateTimeCalendar(const IFWL_App* app,
-                        std::unique_ptr<CFWL_WidgetProperties> properties,
-                        IFWL_Widget* pOuter);
-
-  // IFWL_MonthCalendar
-  void OnProcessMessage(CFWL_Message* pMessage) override;
-
- private:
-  void OnLButtonDownEx(CFWL_MsgMouse* pMsg);
-  void OnLButtonUpEx(CFWL_MsgMouse* pMsg);
-  void OnMouseMoveEx(CFWL_MsgMouse* pMsg);
-  void DisForm_OnProcessMessage(CFWL_Message* pMessage);
-  void DisForm_OnLButtonUpEx(CFWL_MsgMouse* pMsg);
-
-  bool m_bFlag;
-};
-
-#endif  // XFA_FWL_CORE_IFWL_DATETIMECALENDAR_H_