Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_evtpostdropdown.cpp

Index: xfa/fwl/core/cfwl_evtpostdropdown.cpp
diff --git a/xfa/fwl/core/cfwl_evtpostdropdown.cpp b/xfa/fwl/core/cfwl_evtpostdropdown.cpp
deleted file mode 100644
index 52ba80319720c8788e3ee2835d2becac475f6c84..0000000000000000000000000000000000000000
--- a/xfa/fwl/core/cfwl_evtpostdropdown.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_evtpostdropdown.h"
-
-CFWL_EvtPostDropDown::CFWL_EvtPostDropDown() {}
-
-CFWL_EvtPostDropDown::~CFWL_EvtPostDropDown() {}
-
-CFWL_EventType CFWL_EvtPostDropDown::GetClassID() const {
-  return CFWL_EventType::PostDropDown;
-}