Convert FWL_ERR into an enum class.

xfa/fxfa/app/xfa_ffpushbutton.cpp

Index: xfa/fxfa/app/xfa_ffpushbutton.cpp
diff --git a/xfa/fxfa/app/xfa_ffpushbutton.cpp b/xfa/fxfa/app/xfa_ffpushbutton.cpp
index 6db2b7078c6d5d0f51d65798ec69bb2d34d03ecc..e79812d5deb94e65ca6dfd6e8f614473e014bec7 100644
--- a/xfa/fxfa/app/xfa_ffpushbutton.cpp
+++ b/xfa/fxfa/app/xfa_ffpushbutton.cpp
@@ -204,12 +204,12 @@ void CXFA_FFPushButton::RenderHighlightCaption(CFX_Graphics* pGS,
 int32_t CXFA_FFPushButton::OnProcessMessage(CFWL_Message* pMessage) {
   return m_pOldDelegate->OnProcessMessage(pMessage);
 }
-FWL_ERR CXFA_FFPushButton::OnProcessEvent(CFWL_Event* pEvent) {
+FWL_Error CXFA_FFPushButton::OnProcessEvent(CFWL_Event* pEvent) {
   m_pOldDelegate->OnProcessEvent(pEvent);
   return CXFA_FFField::OnProcessEvent(pEvent);
 }
-FWL_ERR CXFA_FFPushButton::OnDrawWidget(CFX_Graphics* pGraphics,
-                                        const CFX_Matrix* pMatrix) {
+FWL_Error CXFA_FFPushButton::OnDrawWidget(CFX_Graphics* pGraphics,
+                                          const CFX_Matrix* pMatrix) {
   if (m_pNormalWidget->GetStylesEx() & XFA_FWL_PSBSTYLEEXT_HiliteInverted) {
     if ((m_pNormalWidget->GetStates() & FWL_STATE_PSB_Pressed) &&
         (m_pNormalWidget->GetStates() & FWL_STATE_PSB_Hovered)) {
@@ -242,5 +242,5 @@ FWL_ERR CXFA_FFPushButton::OnDrawWidget(CFX_Graphics* pGraphics,
     }
   } else if (m_pNormalWidget->GetStylesEx() & XFA_FWL_PSBSTYLEEXT_HilitePush) {
   }
-  return FWL_ERR_Succeeded;
+  return FWL_Error::Succeeded;
 }