Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_evtpredropdown.cpp

Index: xfa/fwl/core/cfwl_evtpredropdown.cpp
diff --git a/xfa/fwl/core/cfwl_evtpredropdown.cpp b/xfa/fwl/core/cfwl_evtpredropdown.cpp
deleted file mode 100644
index 12fe9fc727bb683d9245a72b0039cdb54f45242c..0000000000000000000000000000000000000000
--- a/xfa/fwl/core/cfwl_evtpredropdown.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2016 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/cfwl_evtpredropdown.h"
-
-CFWL_EvtPreDropDown::CFWL_EvtPreDropDown() {}
-
-CFWL_EvtPreDropDown::~CFWL_EvtPreDropDown() {}
-
-CFWL_EventType CFWL_EvtPreDropDown::GetClassID() const {
-  return CFWL_EventType::PreDropDown;
-}