Convert FWL_ERR into an enum class.

xfa/fwl/basewidget/ifwl_caret.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_CARET_H_
 #define XFA_FWL_BASEWIDGET_IFWL_CARET_H_
 
 #include "xfa/fwl/core/ifwl_widget.h"
 #include "xfa/fwl/core/cfwl_widgetimpproperties.h"
 
 #define FWL_CLASS_Caret L"FWL_CARET"
 #define FWL_CLASSHASH_Caret 671181879
 #define FWL_STATE_CAT_HightLight 1
 
 class IFWL_Caret : public IFWL_Widget {
  public:
   static IFWL_Caret* Create(const CFWL_WidgetImpProperties& properties,
                             IFWL_Widget* pOuter);
 
-  FWL_ERR ShowCaret(FX_BOOL bFlag = TRUE);
-  FWL_ERR GetFrequency(uint32_t& elapse);
-  FWL_ERR SetFrequency(uint32_t elapse);
-  FWL_ERR SetColor(CFX_Color crFill);
+  FWL_Error ShowCaret(FX_BOOL bFlag = TRUE);
+  FWL_Error GetFrequency(uint32_t& elapse);
+  FWL_Error SetFrequency(uint32_t elapse);
+  FWL_Error SetColor(CFX_Color crFill);
 
  protected:
   IFWL_Caret();
 };
 
 #endif  // XFA_FWL_BASEWIDGET_IFWL_CARET_H_