Move the fpdfsdk/include/pdfwindow/ headers into fpdfsdk/pdfwindow.

fpdfsdk/include/pdfwindow/PWL_SpecialButton.h

-// Copyright 2014 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 FPDFSDK_INCLUDE_PDFWINDOW_PWL_SPECIALBUTTON_H_
-#define FPDFSDK_INCLUDE_PDFWINDOW_PWL_SPECIALBUTTON_H_
-
-#include "fpdfsdk/include/pdfwindow/PWL_Button.h"
-
-class CPWL_PushButton : public CPWL_Button {
- public:
-  CPWL_PushButton();
-  ~CPWL_PushButton() override;
-
-  // CPWL_Button
-  CFX_ByteString GetClassName() const override;
-  CFX_FloatRect GetFocusRect() const override;
-};
-
-class CPWL_CheckBox : public CPWL_Button {
- public:
-  CPWL_CheckBox();
-  ~CPWL_CheckBox() override;
-
-  // CPWL_Button
-  CFX_ByteString GetClassName() const override;
-  FX_BOOL OnLButtonUp(const CFX_FloatPoint& point, FX_DWORD nFlag) override;
-  FX_BOOL OnChar(uint16_t nChar, FX_DWORD nFlag) override;
-
-  void SetCheck(bool bCheck);
-  bool IsChecked() const;
-
- private:
-  bool m_bChecked;
-};
-
-class CPWL_RadioButton : public CPWL_Button {
- public:
-  CPWL_RadioButton();
-  ~CPWL_RadioButton() override;
-
-  // CPWL_Button
-  CFX_ByteString GetClassName() const override;
-  FX_BOOL OnLButtonUp(const CFX_FloatPoint& point, FX_DWORD nFlag) override;
-  FX_BOOL OnChar(uint16_t nChar, FX_DWORD nFlag) override;
-
-  void SetCheck(bool bCheck);
-  bool IsChecked() const;
-
- private:
-  bool m_bChecked;
-};
-
-#endif  // FPDFSDK_INCLUDE_PDFWINDOW_PWL_SPECIALBUTTON_H_