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

xfa/fxfa/app/xfa_fwltheme.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/fxfa/app/xfa_fwltheme.h"
 
 #include "xfa/fde/tto/fde_textout.h"
 #include "xfa/fgas/crt/fgas_codepage.h"
@@ skipping 17 matching lines @@
 namespace {
 
 const FX_WCHAR* const g_FWLTheme_CalFonts[] = {
     L"Arial", L"Courier New", L"DejaVu Sans",
 };
 
 }  // namespace
 
 CXFA_FFWidget* XFA_ThemeGetOuterWidget(IFWL_Widget* pWidget) {
   IFWL_Widget* pOuter = pWidget;
-  while (pOuter->GetOuter()) {
+  while (pOuter && pOuter->GetOuter())
     pOuter = pOuter->GetOuter();
-  }
-  if (pOuter) {
-    return (CXFA_FFWidget*)pOuter->GetPrivateData(pOuter);
-  }
-  return NULL;
+
+  return pOuter ? static_cast<CXFA_FFWidget*>(pOuter->GetLayoutItem())
+                : nullptr;
 }
+
 CXFA_FWLTheme::CXFA_FWLTheme(CXFA_FFApp* pApp) : m_pApp(pApp) {
   m_dwCapacity = 0;
   m_fCapacity = 0;
   m_pCalendarFont = NULL;
   m_Rect.Set(0, 0, 0, 0);
   m_pCheckBoxTP = new CXFA_FWLCheckBoxTP;
   m_pListBoxTP = new CFWL_ListBoxTP;
   m_pPictureBoxTP = new CFWL_PictureBoxTP;
   m_pSrollBarTP = new CFWL_ScrollBarTP;
   m_pEditTP = new CXFA_FWLEditTP;
@@ skipping 424 matching lines @@
       }
     }
     CFX_Color crLine(cr);
     pParams->m_pGraphics->SetStrokeColor(&crLine);
     pParams->m_pGraphics->SetLineWidth(fWidth);
     pParams->m_pGraphics->StrokePath(pParams->m_pPath, &pParams->m_matrix);
     return TRUE;
   }
   return CFWL_EditTP::DrawBackground(pParams);
 }