Move fpdfsdk/include/formfiller to fpdfsdk/formfiller.

fpdfsdk/include/formfiller/FFL_PushButton.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_FORMFILLER_FFL_PUSHBUTTON_H_
-#define FPDFSDK_INCLUDE_FORMFILLER_FFL_PUSHBUTTON_H_
-
-#include "fpdfsdk/include/formfiller/FFL_FormFiller.h"
-
-class CFFL_PushButton : public CFFL_Button {
- public:
-  CFFL_PushButton(CPDFDoc_Environment* pApp, CPDFSDK_Annot* pAnnot);
-  ~CFFL_PushButton() override;
-
-  // CFFL_Button
-  CPWL_Wnd* NewPDFWindow(const PWL_CREATEPARAM& cp,
-                         CPDFSDK_PageView* pPageView) override;
-  FX_BOOL OnChar(CPDFSDK_Annot* pAnnot, FX_UINT nChar, FX_UINT nFlags) override;
-  void OnDraw(CPDFSDK_PageView* pPageView,
-              CPDFSDK_Annot* pAnnot,
-              CFX_RenderDevice* pDevice,
-              CFX_Matrix* pUser2Device,
-              FX_DWORD dwFlags) override;
-};
-
-#endif  // FPDFSDK_INCLUDE_FORMFILLER_FFL_PUSHBUTTON_H_