Cleanup FWL Event and Message code.

xfa/fwl/core/cfwl_msgkillfocus.cpp

 // 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_msgkillfocus.h"
 
 #include <memory>
 
 #include "third_party/base/ptr_util.h"
 
-CFWL_MsgKillFocus::CFWL_MsgKillFocus() {}
+CFWL_MsgKillFocus::CFWL_MsgKillFocus(CFWL_Widget* pSrcTarget)
+    : CFWL_MsgKillFocus(pSrcTarget, nullptr) {}
+
+CFWL_MsgKillFocus::CFWL_MsgKillFocus(CFWL_Widget* pSrcTarget,
+                                     CFWL_Widget* pDstTarget)
+    : CFWL_Message(CFWL_Message::Type::KillFocus, pSrcTarget, pDstTarget) {}
 
 CFWL_MsgKillFocus::~CFWL_MsgKillFocus() {}
 
 std::unique_ptr<CFWL_Message> CFWL_MsgKillFocus::Clone() {
   return pdfium::MakeUnique<CFWL_MsgKillFocus>(*this);
 }
-
-CFWL_MessageType CFWL_MsgKillFocus::GetClassID() const {
-  return CFWL_MessageType::KillFocus;
-}