Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_evtpredropdown.h

Index: xfa/fwl/core/cfwl_evtpredropdown.h
diff --git a/xfa/fwl/core/cfwl_evtpredropdown.h b/xfa/fwl/core/cfwl_evtpredropdown.h
deleted file mode 100644
index df4d29abe4786a9ec68bf168992d8d211ec826ab..0000000000000000000000000000000000000000
--- a/xfa/fwl/core/cfwl_evtpredropdown.h
+++ /dev/null
@@ -1,20 +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
-
-#ifndef XFA_FWL_CORE_CFWL_EVTPREDROPDOWN_H_
-#define XFA_FWL_CORE_CFWL_EVTPREDROPDOWN_H_
-
-#include "xfa/fwl/core/cfwl_event.h"
-
-class CFWL_EvtPreDropDown : public CFWL_Event {
- public:
-  CFWL_EvtPreDropDown();
-  ~CFWL_EvtPreDropDown() override;
-
-  CFWL_EventType GetClassID() const override;
-};
-
-#endif  // XFA_FWL_CORE_CFWL_EVTPREDROPDOWN_H_