Convert FWL_ERR into an enum class.

xfa/fxfa/app/xfa_ffimageedit.h

Index: xfa/fxfa/app/xfa_ffimageedit.h
diff --git a/xfa/fxfa/app/xfa_ffimageedit.h b/xfa/fxfa/app/xfa_ffimageedit.h
index 1acc13c7fab0a771b5ad952c87703d7de3d4bc1e..fb3e21e19f769ca55824000bdc8f0fe2e27aa64c 100644
--- a/xfa/fxfa/app/xfa_ffimageedit.h
+++ b/xfa/fxfa/app/xfa_ffimageedit.h
@@ -21,10 +21,10 @@ class CXFA_FFImageEdit : public CXFA_FFField {
   virtual FX_BOOL LoadWidget();
   virtual void UnloadWidget();
   virtual FX_BOOL OnLButtonDown(uint32_t dwFlags, FX_FLOAT fx, FX_FLOAT fy);
-  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:
   virtual void SetFWLRect();