Move the message definitions to their own files.

xfa/fwl/core/ifwl_monthcalendar.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_monthcalendar.h"
 
 #include <algorithm>
 
 #include "third_party/base/ptr_util.h"
 #include "xfa/fde/tto/fde_textout.h"
-#include "xfa/fwl/core/cfwl_message.h"
+#include "xfa/fwl/core/cfwl_msgmouse.h"
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/cfwl_themetext.h"
 #include "xfa/fwl/core/fwl_noteimp.h"
 #include "xfa/fwl/core/ifwl_datetimepicker.h"
 #include "xfa/fwl/core/ifwl_formproxy.h"
 #include "xfa/fwl/core/ifwl_monthcalendar.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 
 #define MONTHCAL_HSEP_HEIGHT 1
 #define MONTHCAL_VSEP_WIDTH 1
@@ skipping 1084 matching lines @@
                                        uint32_t dwSt,
                                        CFX_RectF rc,
                                        CFX_WideString& wsday)
     : iDay(day),
       iDayOfWeek(dayofweek),
       dwStates(dwSt),
       rect(rc),
       wsDay(wsday) {}
 
 IFWL_MonthCalendar::DATEINFO::~DATEINFO() {}