Convert FWL_ERR into an enum class.

xfa/fwl/theme/cfwl_edittp.cpp

Index: xfa/fwl/theme/cfwl_edittp.cpp
diff --git a/xfa/fwl/theme/cfwl_edittp.cpp b/xfa/fwl/theme/cfwl_edittp.cpp
index e557e6606bf1722ccc0714632dccac226829d8b1..644da90071e68c6c58d51ef261fad1893bf0ef8e 100644
--- a/xfa/fwl/theme/cfwl_edittp.cpp
+++ b/xfa/fwl/theme/cfwl_edittp.cpp
@@ -77,11 +77,11 @@ FX_BOOL CFWL_EditTP::DrawBackground(CFWL_ThemeBackground* pParams) {
   }
   return TRUE;
 }
-FWL_ERR CFWL_EditTP::Initialize() {
+FWL_Error CFWL_EditTP::Initialize() {
   InitTTO();
   return CFWL_WidgetTP::Initialize();
 }
-FWL_ERR CFWL_EditTP::Finalize() {
+FWL_Error CFWL_EditTP::Finalize() {
   FinalizeTTO();
   return CFWL_WidgetTP::Finalize();
 }