Move xfa/fwl/core to xfa/fwl.

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_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);
-}