Change IFWL_Widget to store a single delegate.

xfa/fwl/core/ifwl_form.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/ifwl_form.h"
 
 #include "third_party/base/ptr_util.h"
 #include "xfa/fde/tto/fde_textout.h"
@@ skipping 803 matching lines @@
     case CFWL_MessageType::Deactivate: {
       m_pOwner->m_pProperties->m_dwStates |= FWL_WGTSTATE_Deactivated;
       const IFWL_App* pApp = m_pOwner->GetOwnerApp();
       CFWL_NoteDriver* pDriver =
           static_cast<CFWL_NoteDriver*>(pApp->GetNoteDriver());
       IFWL_Widget* pSubFocus = m_pOwner->GetSubFocus();
       if (pSubFocus) {
         if (pSubFocus == pDriver->GetFocus()) {
           pDriver->SetFocus(nullptr);
         } else if (pSubFocus->GetStates() & FWL_WGTSTATE_Focused) {
-          if (IFWL_WidgetDelegate* pDelegate =
-                  pSubFocus->GetCurrentDelegate()) {
+          if (IFWL_WidgetDelegate* pDelegate = pSubFocus->GetDelegate()) {
             CFWL_MsgKillFocus ms;
             pDelegate->OnProcessMessage(&ms);
           }
         }
       }
       m_pOwner->Repaint(&m_pOwner->m_rtRelative);
       break;
     }
     case CFWL_MessageType::Mouse: {
       CFWL_MsgMouse* pMsg = static_cast<CFWL_MsgMouse*>(pMessage);
@@ skipping 250 matching lines @@
 
 uint32_t CFWL_SysBtn::GetPartState() const {
   if (IsDisabled())
     return CFWL_PartState_Disabled;
   if (m_dwState & FWL_SYSBUTTONSTATE_Pressed)
     return CFWL_PartState_Pressed;
   if (m_dwState & FWL_SYSBUTTONSTATE_Hover)
     return CFWL_PartState_Hovered;
   return CFWL_PartState_Normal;
 }