Add opaque "layout item" to widgets for caller's use.

xfa/fxfa/app/xfa_fwladapter.cpp

Index: xfa/fxfa/app/xfa_fwladapter.cpp
diff --git a/xfa/fxfa/app/xfa_fwladapter.cpp b/xfa/fxfa/app/xfa_fwladapter.cpp
index 4a0828b5ef9b506d0170485b5f9216056a80239b..dbce492dab0526d247c3e8a34e8851baec27d2c1 100644
--- a/xfa/fxfa/app/xfa_fwladapter.cpp
+++ b/xfa/fxfa/app/xfa_fwladapter.cpp
@@ -18,7 +18,7 @@ FWL_Error CXFA_FWLAdapterWidgetMgr::RepaintWidget(IFWL_Widget* pWidget,
   if (!pWidget)
     return FWL_Error::Indefinite;
 
-  CXFA_FFField* pField = (CXFA_FFField*)pWidget->GetPrivateData(pWidget);
+  CXFA_FFField* pField = static_cast<CXFA_FFField*>(pWidget->GetLayoutItem());
   if (!pField)
     return FWL_Error::Indefinite;
 
@@ -31,7 +31,8 @@ FX_BOOL CXFA_FWLAdapterWidgetMgr::GetPopupPos(IFWL_Widget* pWidget,
                                               FX_FLOAT fMaxHeight,
                                               const CFX_RectF& rtAnchor,
                                               CFX_RectF& rtPopup) {
-  CXFA_FFWidget* pFFWidget = (CXFA_FFWidget*)(pWidget->GetPrivateData(pWidget));
+  CXFA_FFWidget* pFFWidget =
+      static_cast<CXFA_FFWidget*>(pWidget->GetLayoutItem());
   CFX_Matrix mt;
   pFFWidget->GetRotateMatrix(mt);
   CFX_RectF rtRotateAnchor(rtAnchor);