Remove include only fwl.h and IWYU.

xfa/include/fwl/basewidget/fwl_scrollbar.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_BASEWIDGET_FWL_SCROLLBAR_H_
 #define XFA_INCLUDE_FWL_BASEWIDGET_FWL_SCROLLBAR_H_
 
-class CFWL_WidgetImpProperties;
-class IFWL_Widget;
-class IFWL_ScrollBarDP;
-class IFWL_ScrollBar;
+#include "xfa/src/fwl/src/core/include/fwl_widgetimp.h"
+
 #define FWL_CLASS_ScrollBar L"FWL_SCROLLBAR"
 #define FWL_CLASSHASH_ScrollBar 2826584844
 #define FWL_STYLEEXT_SCB_Horz (0L << 0)
 #define FWL_STYLEEXT_SCB_Vert (1L << 0)
 #define FWL_PART_SCB_Border 1
 #define FWL_PART_SCB_Edge 2
 #define FWL_PART_SCB_Background 3
 #define FWL_PART_SCB_ForeArrow 4
 #define FWL_PART_SCB_BackArrow 5
 #define FWL_PART_SCB_Thumb 6
 #define FWL_PART_SCB_LowerTrack 7
 #define FWL_PART_SCB_UpperTrack 8
 #define FWL_PARTSTATE_SCB_Normal (0L << 0)
 #define FWL_PARTSTATE_SCB_Hovered (1L << 0)
 #define FWL_PARTSTATE_SCB_Pressed (2L << 0)
 #define FWL_PARTSTATE_SCB_Disabled (3L << 0)
 #define FWL_WGTHITTEST_SCB_ForeArrow FWL_WGTHITTEST_MAX + 1
 #define FWL_WGTHITTEST_SCB_BackArrow FWL_WGTHITTEST_MAX + 2
 #define FWL_WGTHITTEST_SCB_LowerTrack FWL_WGTHITTEST_MAX + 3
 #define FWL_WGTHITTEST_SCB_UpperTrack FWL_WGTHITTEST_MAX + 4
 #define FWL_WGTHITTEST_SCB_Thumb FWL_WGTHITTEST_MAX + 5
 #define FWL_CAPACITY_SCB_Size FWL_WGTCAPACITY_MAX
+
 enum FWL_SCBCODE {
   FWL_SCBCODE_None = 1,
   FWL_SCBCODE_Min,
   FWL_SCBCODE_Max,
   FWL_SCBCODE_PageBackward,
   FWL_SCBCODE_PageForward,
   FWL_SCBCODE_StepBackward,
   FWL_SCBCODE_StepForward,
   FWL_SCBCODE_Pos,
   FWL_SCBCODE_TrackPos,
   FWL_SCBCODE_EndScroll,
 };
+
 class IFWL_ScrollBarDP : public IFWL_DataProvider {};
+
 class IFWL_ScrollBar : public IFWL_Widget {
  public:
   static IFWL_ScrollBar* Create(const CFWL_WidgetImpProperties& properties,
                                 IFWL_Widget* pOuter);
 
   FX_BOOL IsVertical();
   FWL_ERR GetRange(FX_FLOAT& fMin, FX_FLOAT& fMax);
   FWL_ERR SetRange(FX_FLOAT fMin, FX_FLOAT fMax);
   FX_FLOAT GetPageSize();
   FWL_ERR SetPageSize(FX_FLOAT fPageSize);
   FX_FLOAT GetStepSize();
   FWL_ERR SetStepSize(FX_FLOAT fStepSize);
   FX_FLOAT GetPos();
   FWL_ERR SetPos(FX_FLOAT fPos);
   FX_FLOAT GetTrackPos();
   FWL_ERR SetTrackPos(FX_FLOAT fTrackPos);
   FX_BOOL DoScroll(FX_DWORD dwCode, FX_FLOAT fPos = 0.0f);
 
  protected:
   IFWL_ScrollBar();
 };
 
 #endif  // XFA_INCLUDE_FWL_BASEWIDGET_FWL_SCROLLBAR_H_