Convert FWL_ERR into an enum class.

xfa/fxgraphics/cagg_graphics.h

 // Copyright 2016 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_FXGRAPHICS_CAGG_GRAPHICS_H_
 #define XFA_FXGRAPHICS_CAGG_GRAPHICS_H_
 
 #include "core/fxge/include/fx_dib.h"
 #include "xfa/fxgraphics/include/cfx_graphics.h"
 
 class CFX_Graphics;
 
 class CAGG_Graphics {
  public:
   CAGG_Graphics();
   virtual ~CAGG_Graphics();
 
-  FX_ERR Create(CFX_Graphics* owner,
-                int32_t width,
-                int32_t height,
-                FXDIB_Format format);
+  FWL_Error Create(CFX_Graphics* owner,
+                   int32_t width,
+                   int32_t height,
+                   FXDIB_Format format);
 
  private:
   CFX_Graphics* m_owner;
 };
 
 #endif  // XFA_FXGRAPHICS_CAGG_GRAPHICS_H_