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

xfa/fwl/lightwidget/cfwl_widget.cpp

Index: xfa/fwl/lightwidget/cfwl_widget.cpp
diff --git a/xfa/fwl/lightwidget/cfwl_widget.cpp b/xfa/fwl/lightwidget/cfwl_widget.cpp
index 0258c274892bcb9a9a35e75982e4eac2fe239418..239796d03ae628a94d4726c1b59142ddf3fad94f 100644
--- a/xfa/fwl/lightwidget/cfwl_widget.cpp
+++ b/xfa/fwl/lightwidget/cfwl_widget.cpp
@@ -124,9 +124,7 @@ FWL_Error CFWL_Widget::ModifyStylesEx(uint32_t dwStylesExAdded,
 }
 
 uint32_t CFWL_Widget::GetStates() {
-  if (!m_pIface)
-    return 0;
-  return m_pIface->GetStates();
+  return m_pIface ? m_pIface->GetStates() : 0;
 }
 
 void CFWL_Widget::SetStates(uint32_t dwStates, FX_BOOL bSet) {
@@ -134,6 +132,15 @@ void CFWL_Widget::SetStates(uint32_t dwStates, FX_BOOL bSet) {
     m_pIface->SetStates(dwStates, bSet);
 }
 
+void* CFWL_Widget::GetLayoutItem() const {
+  return m_pIface ? m_pIface->GetLayoutItem() : nullptr;
+}
+
+void CFWL_Widget::SetLayoutItem(void* pItem) {
+  if (m_pIface)
+    m_pIface->SetLayoutItem(pItem);
+}
+
 FWL_Error CFWL_Widget::SetPrivateData(void* module_id,
                                       void* pData,
                                       PD_CALLBACK_FREEDATA callback) {