Convert FWL_ERR into an enum class.

xfa/fxfa/app/xfa_ffchoicelist.h

Index: xfa/fxfa/app/xfa_ffchoicelist.h
diff --git a/xfa/fxfa/app/xfa_ffchoicelist.h b/xfa/fxfa/app/xfa_ffchoicelist.h
index ba4838013869feee97522d8cb357d13dca1a3a76..c59ca647aa2b59d8c7d9dd2e9e3d25a224a2b930 100644
--- a/xfa/fxfa/app/xfa_ffchoicelist.h
+++ b/xfa/fxfa/app/xfa_ffchoicelist.h
@@ -28,10 +28,10 @@ class CXFA_FFListBox : public CXFA_FFField {
   void SetItemState(int32_t nIndex, FX_BOOL bSelected);
   void InsertItem(const CFX_WideStringC& wsLabel, int32_t nIndex = -1);
   void DeleteItem(int32_t nIndex);
-  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:
   IFWL_WidgetDelegate* m_pOldDelegate;
@@ -84,10 +84,10 @@ class CXFA_FFComboBox : public CXFA_FFField {
   void SetItemState(int32_t nIndex, FX_BOOL bSelected);
   void InsertItem(const CFX_WideStringC& wsLabel, int32_t nIndex = -1);
   void DeleteItem(int32_t nIndex);
-  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:
   IFWL_WidgetDelegate* m_pOldDelegate;