Remove xfa/src/fwl/src and move code up a level.

xfa/src/fwl/lightwidget/listbox.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/include/fwl/lightwidget/listbox.h"
 
 #include <memory>
 
@@ skipping 282 matching lines @@
 FX_DWORD CFWL_ListBox::CFWL_ListBoxDP::GetItemCheckState(IFWL_Widget* pWidget,
                                                          FWL_HLISTITEM hItem) {
   return reinterpret_cast<CFWL_ListItem*>(hItem)->m_dwCheckState;
 }
 FWL_ERR CFWL_ListBox::CFWL_ListBoxDP::SetItemCheckState(IFWL_Widget* pWidget,
                                                         FWL_HLISTITEM hItem,
                                                         FX_DWORD dwCheckState) {
   reinterpret_cast<CFWL_ListItem*>(hItem)->m_dwCheckState = dwCheckState;
   return FWL_ERR_Succeeded;
 }