Move the message definitions to their own files.

xfa/fwl/core/ifwl_scrollbar.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_scrollbar.h"
 
 #include "third_party/base/ptr_util.h"
-#include "xfa/fwl/core/cfwl_message.h"
+#include "xfa/fwl/core/cfwl_msgmouse.h"
+#include "xfa/fwl/core/cfwl_msgmousewheel.h"
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/cfwl_themepart.h"
 #include "xfa/fwl/core/fwl_noteimp.h"
 #include "xfa/fwl/core/ifwl_scrollbar.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 
 #define FWL_SCROLLBAR_Elapse 500
 #define FWL_SCROLLBAR_MinThumb 5
 
 IFWL_ScrollBar::IFWL_ScrollBar(
@@ skipping 628 matching lines @@
 
 void IFWL_ScrollBar::Timer::Run(IFWL_TimerInfo* pTimerInfo) {
   IFWL_ScrollBar* pButton = static_cast<IFWL_ScrollBar*>(m_pWidget);
 
   if (pButton->m_pTimerInfo)
     pButton->m_pTimerInfo->StopTimer();
 
   if (!pButton->SendEvent())
     pButton->m_pTimerInfo = StartTimer(0, true);
 }