Move the message definitions to their own files.

xfa/fxfa/app/xfa_ffcheckbutton.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/fxfa/app/xfa_ffcheckbutton.h"
 
 #include "xfa/fwl/core/cfwl_checkbox.h"
-#include "xfa/fwl/core/cfwl_message.h"
+#include "xfa/fwl/core/cfwl_msgmouse.h"
 #include "xfa/fwl/core/cfwl_widgetmgr.h"
 #include "xfa/fwl/core/fwl_noteimp.h"
 #include "xfa/fxfa/app/xfa_ffexclgroup.h"
 #include "xfa/fxfa/app/xfa_fffield.h"
 #include "xfa/fxfa/xfa_ffapp.h"
 #include "xfa/fxfa/xfa_ffdoc.h"
 #include "xfa/fxfa/xfa_ffdocview.h"
 #include "xfa/fxfa/xfa_ffpageview.h"
 #include "xfa/fxfa/xfa_ffwidget.h"
 
@@ skipping 310 matching lines @@
     default:
       break;
   }
   m_pOldDelegate->OnProcessEvent(pEvent);
 }
 
 void CXFA_FFCheckButton::OnDrawWidget(CFX_Graphics* pGraphics,
                                       const CFX_Matrix* pMatrix) {
   m_pOldDelegate->OnDrawWidget(pGraphics, pMatrix);
 }