Change IFWL_Widget to store a single delegate.

xfa/fwl/core/cfwl_widget.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/fwl/core/cfwl_widget.h"
 
 #include "xfa/fde/tto/fde_textout.h"
 #include "xfa/fwl/core/cfwl_themetext.h"
@@ skipping 109 matching lines @@
   return m_pIface->HitTest(fx, fy);
 }
 
 FWL_Error CFWL_Widget::DrawWidget(CFX_Graphics* pGraphics,
                                   const CFX_Matrix* pMatrix) {
   if (!m_pIface)
     return FWL_Error::Indefinite;
   return m_pIface->DrawWidget(pGraphics, pMatrix);
 }
 
-IFWL_WidgetDelegate* CFWL_Widget::GetCurrentDelegate() {
-  return m_pIface ? m_pIface->GetCurrentDelegate() : nullptr;
+std::unique_ptr<IFWL_WidgetDelegate> CFWL_Widget::ReleaseDelegate() {
+  return m_pIface ? m_pIface->ReleaseDelegate() : nullptr;
 }
 
-void CFWL_Widget::SetCurrentDelegate(IFWL_WidgetDelegate* pDelegate) {
+void CFWL_Widget::SetDelegate(std::unique_ptr<IFWL_WidgetDelegate> pDelegate) {
   if (m_pIface)
-    m_pIface->SetCurrentDelegate(pDelegate);
+    m_pIface->SetDelegate(std::move(pDelegate));
 }