Cleanup remaining IFWL files for visiblity and usage.

xfa/fwl/core/cfwl_checkbox.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_FWL_CORE_CFWL_CHECKBOX_H_
 #define XFA_FWL_CORE_CFWL_CHECKBOX_H_
 
 #include "xfa/fwl/core/cfwl_widget.h"
 #include "xfa/fwl/core/ifwl_checkbox.h"
 
 class CFWL_CheckBox : public CFWL_Widget, public IFWL_CheckBoxDP {
  public:
   CFWL_CheckBox(const IFWL_App*);
   ~CFWL_CheckBox() override;
 
   void Initialize();
 
-  FWL_Error SetCaption(const CFX_WideStringC& wsCaption);
-  FWL_Error SetBoxSize(FX_FLOAT fHeight);
-  int32_t GetCheckState();
-  FWL_Error SetCheckState(int32_t iCheck);
-
   // IFWL_DataProvider
   void GetCaption(IFWL_Widget* pWidget, CFX_WideString& wsCaption) override;
 
   // IFWL_CheckBoxDP
   FX_FLOAT GetBoxSize(IFWL_Widget* pWidget) override;
 
+  void SetBoxSize(FX_FLOAT fHeight);
+
  private:
   FX_FLOAT m_fBoxHeight;
   CFX_WideString m_wsCaption;
 };
 
 #endif  // XFA_FWL_CORE_CFWL_CHECKBOX_H_