Convert single use EventTypes to class files.

xfa/fwl/core/cfwl_evtpredropdown.cpp

Index: xfa/fwl/core/cfwl_evtpredropdown.cpp
diff --git a/xfa/fwl/core/cfwl_evtclose.cpp b/xfa/fwl/core/cfwl_evtpredropdown.cpp
similarity index 51%
copy from xfa/fwl/core/cfwl_evtclose.cpp
copy to xfa/fwl/core/cfwl_evtpredropdown.cpp
index 72713a17d1b2ace83cab49f6506ef27bca11fc2d..12fe9fc727bb683d9245a72b0039cdb54f45242c 100644
--- a/xfa/fwl/core/cfwl_evtclose.cpp
+++ b/xfa/fwl/core/cfwl_evtpredropdown.cpp
@@ -4,12 +4,12 @@
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
-#include "xfa/fwl/core/cfwl_evtclose.h"
+#include "xfa/fwl/core/cfwl_evtpredropdown.h"
 
-CFWL_EvtClose::CFWL_EvtClose() {}
+CFWL_EvtPreDropDown::CFWL_EvtPreDropDown() {}
 
-CFWL_EvtClose::~CFWL_EvtClose() {}
+CFWL_EvtPreDropDown::~CFWL_EvtPreDropDown() {}
 
-CFWL_EventType CFWL_EvtClose::GetClassID() const {
-  return CFWL_EventType::Close;
+CFWL_EventType CFWL_EvtPreDropDown::GetClassID() const {
+  return CFWL_EventType::PreDropDown;
 }