Convert FWL_ERR into an enum class.

xfa/fwl/lightwidget/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_LIGHTWIDGET_CFWL_CHECKBOX_H_
 #define XFA_FWL_LIGHTWIDGET_CFWL_CHECKBOX_H_
 
 #include "xfa/fwl/basewidget/ifwl_checkbox.h"
 #include "xfa/fwl/lightwidget/cfwl_widget.h"
 
 class CFWL_CheckBox : public CFWL_Widget {
  public:
   static CFWL_CheckBox* Create();
 
-  FWL_ERR Initialize(const CFWL_WidgetProperties* pProperties = NULL);
-  FWL_ERR GetCaption(CFX_WideString& wsCaption);
-  FWL_ERR SetCaption(const CFX_WideStringC& wsCaption);
-  FWL_ERR SetBoxSize(FX_FLOAT fHeight);
+  FWL_Error Initialize(const CFWL_WidgetProperties* pProperties = NULL);
+  FWL_Error GetCaption(CFX_WideString& wsCaption);
+  FWL_Error SetCaption(const CFX_WideStringC& wsCaption);
+  FWL_Error SetBoxSize(FX_FLOAT fHeight);
   int32_t GetCheckState();
-  FWL_ERR SetCheckState(int32_t iCheck);
+  FWL_Error SetCheckState(int32_t iCheck);
   CFWL_CheckBox();
   virtual ~CFWL_CheckBox();
 
  protected:
   class CFWL_CheckBoxDP : public IFWL_CheckBoxDP {
    public:
     CFWL_CheckBoxDP();
-    virtual FWL_ERR GetCaption(IFWL_Widget* pWidget, CFX_WideString& wsCaption);
+    virtual FWL_Error GetCaption(IFWL_Widget* pWidget,
+                                 CFX_WideString& wsCaption);
     virtual FX_FLOAT GetBoxSize(IFWL_Widget* pWidget);
     FX_FLOAT m_fBoxHeight;
     CFX_WideString m_wsCaption;
   };
   CFWL_CheckBoxDP m_checkboxData;
 };
 
 #endif  // XFA_FWL_LIGHTWIDGET_CFWL_CHECKBOX_H_