Move the message definitions to their own files.

xfa/fwl/core/ifwl_spinbutton.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_spinbutton.h"
 
 #include "third_party/base/ptr_util.h"
-#include "xfa/fwl/core/cfwl_message.h"
+#include "xfa/fwl/core/cfwl_msgkey.h"
+#include "xfa/fwl/core/cfwl_msgmouse.h"
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/cfwl_widgetproperties.h"
 #include "xfa/fwl/core/fwl_noteimp.h"
 #include "xfa/fwl/core/ifwl_spinbutton.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 #include "xfa/fwl/core/ifwl_timer.h"
 
 namespace {
 
@@ skipping 355 matching lines @@
   IFWL_SpinButton* pButton = static_cast<IFWL_SpinButton*>(m_pWidget);
 
   if (!pButton->m_pTimerInfo)
     return;
 
   CFWL_EvtSpbClick wmPosChanged;
   wmPosChanged.m_pSrcTarget = pButton;
   wmPosChanged.m_bUp = pButton->m_iButtonIndex == 0;
   pButton->DispatchEvent(&wmPosChanged);
 }