Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_evtselectchanged.cpp

Index: xfa/fwl/core/cfwl_evtselectchanged.cpp
diff --git a/xfa/fwl/core/cfwl_evtselectchanged.cpp b/xfa/fwl/core/cfwl_evtselectchanged.cpp
index 3eead94d6e1076950c02507f29047dfebabbf85d..811fc9490fae8c5dc22c91272c9876e8e53e4cd4 100644
--- a/xfa/fwl/core/cfwl_evtselectchanged.cpp
+++ b/xfa/fwl/core/cfwl_evtselectchanged.cpp
@@ -6,10 +6,7 @@
 
 #include "xfa/fwl/core/cfwl_evtselectchanged.h"
 
-CFWL_EvtSelectChanged::CFWL_EvtSelectChanged() {}
+CFWL_EvtSelectChanged::CFWL_EvtSelectChanged(CFWL_Widget* pSrcTarget)
+    : CFWL_Event(CFWL_Event::Type::SelectChanged, pSrcTarget) {}
 
 CFWL_EvtSelectChanged::~CFWL_EvtSelectChanged() {}
-
-CFWL_EventType CFWL_EvtSelectChanged::GetClassID() const {
-  return CFWL_EventType::SelectChanged;
-}