Convert FWL_ERR into an enum class.

xfa/fwl/lightwidget/cfwl_pushbutton.cpp

Index: xfa/fwl/lightwidget/cfwl_pushbutton.cpp
diff --git a/xfa/fwl/lightwidget/cfwl_pushbutton.cpp b/xfa/fwl/lightwidget/cfwl_pushbutton.cpp
index 52747bdebed093565a9a06542bc7f6fcf57a4b9c..7c8a9fa64dbcdc3b8c1c5aa4bfbf90ec13528474 100644
--- a/xfa/fwl/lightwidget/cfwl_pushbutton.cpp
+++ b/xfa/fwl/lightwidget/cfwl_pushbutton.cpp
@@ -12,51 +12,52 @@ CFWL_PushButton* CFWL_PushButton::Create() {
   return new CFWL_PushButton;
 }
 
-FWL_ERR CFWL_PushButton::Initialize(const CFWL_WidgetProperties* pProperties) {
+FWL_Error CFWL_PushButton::Initialize(
+    const CFWL_WidgetProperties* pProperties) {
   if (m_pIface)
-    return FWL_ERR_Indefinite;
+    return FWL_Error::Indefinite;
   if (pProperties) {
     *m_pProperties = *pProperties;
   }
   std::unique_ptr<IFWL_PushButton> pPushButton(IFWL_PushButton::Create(
       m_pProperties->MakeWidgetImpProperties(&m_buttonData), nullptr));
-  FWL_ERR ret = pPushButton->Initialize();
-  if (ret != FWL_ERR_Succeeded) {
+  FWL_Error ret = pPushButton->Initialize();
+  if (ret != FWL_Error::Succeeded) {
     return ret;
   }
   m_pIface = pPushButton.release();
   CFWL_Widget::Initialize();
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }
 
-FWL_ERR CFWL_PushButton::GetCaption(CFX_WideString& wsCaption) {
+FWL_Error CFWL_PushButton::GetCaption(CFX_WideString& wsCaption) {
   wsCaption = m_buttonData.m_wsCaption;
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }
 
-FWL_ERR CFWL_PushButton::SetCaption(const CFX_WideStringC& wsCaption) {
+FWL_Error CFWL_PushButton::SetCaption(const CFX_WideStringC& wsCaption) {
   m_buttonData.m_wsCaption = wsCaption;
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }
 
 CFX_DIBitmap* CFWL_PushButton::GetPicture() {
   return m_buttonData.m_pBitmap;
 }
 
-FWL_ERR CFWL_PushButton::SetPicture(CFX_DIBitmap* pBitmap) {
+FWL_Error CFWL_PushButton::SetPicture(CFX_DIBitmap* pBitmap) {
   m_buttonData.m_pBitmap = pBitmap;
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }
 
 CFWL_PushButton::CFWL_PushButton() {}
 
 CFWL_PushButton::~CFWL_PushButton() {}
 
-FWL_ERR CFWL_PushButton::CFWL_PushButtonDP::GetCaption(
+FWL_Error CFWL_PushButton::CFWL_PushButtonDP::GetCaption(
     IFWL_Widget* pWidget,
     CFX_WideString& wsCaption) {
   wsCaption = m_wsCaption;
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }
 
 CFX_DIBitmap* CFWL_PushButton::CFWL_PushButtonDP::GetPicture(