Move xfa/fwl/core to xfa/fwl.

xfa/fwl/core/cfwl_msgkey.h

-// 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_MSGKEY_H_
-#define XFA_FWL_CORE_CFWL_MSGKEY_H_
-
-#include <memory>
-
-#include "xfa/fwl/core/cfwl_message.h"
-
-enum class FWL_KeyCommand { KeyDown, KeyUp, Char };
-
-class CFWL_MsgKey : public CFWL_Message {
- public:
-  CFWL_MsgKey(CFWL_Widget* pSrcTarget, CFWL_Widget* pDstTarget);
-  ~CFWL_MsgKey() override;
-
-  // CFWL_Message
-  std::unique_ptr<CFWL_Message> Clone() override;
-
-  uint32_t m_dwKeyCode;
-  uint32_t m_dwFlags;
-  FWL_KeyCommand m_dwCmd;
-};
-
-#endif  // XFA_FWL_CORE_CFWL_MSGKEY_H_