Convert FWL_ERR into an enum class.

xfa/fwl/basewidget/ifwl_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_BASEWIDGET_IFWL_CHECKBOX_H_
 #define XFA_FWL_BASEWIDGET_IFWL_CHECKBOX_H_
 
 #include "xfa/fwl/core/ifwl_widget.h"
@@ skipping 41 matching lines @@
 class IFWL_CheckBoxDP : public IFWL_DataProvider {
  public:
   virtual FX_FLOAT GetBoxSize(IFWL_Widget* pWidget) = 0;
 };
 
 class IFWL_CheckBox : public IFWL_Widget {
  public:
   static IFWL_CheckBox* Create(const CFWL_WidgetImpProperties& properties,
                                IFWL_Widget* pOuter);
   int32_t GetCheckState();
-  FWL_ERR SetCheckState(int32_t iCheck);
+  FWL_Error SetCheckState(int32_t iCheck);
 
  protected:
   IFWL_CheckBox();
 };
 
 #endif  // XFA_FWL_BASEWIDGET_IFWL_CHECKBOX_H_