Remove include only fwl.h and IWYU.

xfa/include/fwl/lightwidget/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 XFA_INCLUDE_FWL_LIGHTWIDGET_PUSHBUTTON_H_
 #define XFA_INCLUDE_FWL_LIGHTWIDGET_PUSHBUTTON_H_
 
-class CFWL_Widget;
-class CFWL_WidgetProperties;
-class IFWL_PushButtonDP;
-class CFWL_PushButton;
-class CFWL_PushButtonDP;
+#include "xfa/include/fwl/basewidget/fwl_pushbutton.h"
+#include "xfa/include/fwl/lightwidget/widget.h"
+
 class CFWL_PushButton : public CFWL_Widget {
  public:
   static CFWL_PushButton* Create();
   FWL_ERR Initialize(const CFWL_WidgetProperties* pProperties = NULL);
   FWL_ERR GetCaption(CFX_WideString& wsCaption);
   FWL_ERR SetCaption(const CFX_WideStringC& wsCaption);
   CFX_DIBitmap* GetPicture();
   FWL_ERR SetPicture(CFX_DIBitmap* pBitmap);
   CFWL_PushButton();
   virtual ~CFWL_PushButton();
 
  protected:
   class CFWL_PushButtonDP : public IFWL_PushButtonDP {
    public:
     CFWL_PushButtonDP() : m_pBitmap(NULL) {}
     FWL_ERR GetCaption(IFWL_Widget* pWidget, CFX_WideString& wsCaption);
     virtual CFX_DIBitmap* GetPicture(IFWL_Widget* pWidget);
     CFX_WideString m_wsCaption;
     CFX_DIBitmap* m_pBitmap;
   };
   CFWL_PushButtonDP m_buttonData;
 };
 
 #endif  // XFA_INCLUDE_FWL_LIGHTWIDGET_PUSHBUTTON_H_