Convert FWL_ERR into an enum class.

xfa/fxfa/app/xfa_ffpushbutton.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_FXFA_APP_XFA_FFPUSHBUTTON_H_
 #define XFA_FXFA_APP_XFA_FFPUSHBUTTON_H_
 
 #include "xfa/fxfa/app/xfa_fffield.h"
@@ skipping 10 matching lines @@
   CXFA_FFPushButton(CXFA_FFPageView* pPageView, CXFA_WidgetAcc* pDataAcc);
   virtual ~CXFA_FFPushButton();
   virtual void RenderWidget(CFX_Graphics* pGS,
                             CFX_Matrix* pMatrix = NULL,
                             uint32_t dwStatus = 0,
                             int32_t iRotate = 0);
   virtual FX_BOOL LoadWidget();
   virtual void UnloadWidget();
   virtual FX_BOOL PerformLayout();
   virtual void UpdateWidgetProperty();
-  virtual int32_t OnProcessMessage(CFWL_Message* pMessage);
-  virtual FWL_ERR OnProcessEvent(CFWL_Event* pEvent);
-  virtual FWL_ERR OnDrawWidget(CFX_Graphics* pGraphics,
-                               const CFX_Matrix* pMatrix = NULL);
+  virtual void OnProcessMessage(CFWL_Message* pMessage);
+  virtual void OnProcessEvent(CFWL_Event* pEvent);
+  virtual void OnDrawWidget(CFX_Graphics* pGraphics,
+                            const CFX_Matrix* pMatrix = NULL);
 
  protected:
   void LoadHighlightCaption();
   void LayoutHighlightCaption();
   void RenderHighlightCaption(CFX_Graphics* pGS, CFX_Matrix* pMatrix = NULL);
   FX_FLOAT GetLineWidth();
   FX_ARGB GetLineColor();
   FX_ARGB GetFillColor();
   CXFA_TextLayout* m_pRolloverTextLayout;
   CXFA_TextLayout* m_pDownTextLayout;
   CXFA_TextProvider* m_pDownProvider;
   CXFA_TextProvider* m_pRollProvider;
   IFWL_WidgetDelegate* m_pOldDelegate;
 };
 
 #endif  // XFA_FXFA_APP_XFA_FFPUSHBUTTON_H_