Remove FwlEventMask

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 <utility>
 
@@ skipping 43 matching lines @@
       m_iCaptureBtn(-1),
       m_iSysBox(0),
       m_bLButtonDown(false),
       m_bMaximized(false),
       m_bSetMaximize(false),
       m_bDoModalFlag(false) {
   m_rtRelative.Reset();
   m_rtRestore.Reset();
 
   RegisterForm();
-  RegisterEventTarget();
+  RegisterEventTarget(nullptr);
 }
 
 IFWL_Form::~IFWL_Form() {
   UnregisterEventTarget();
   UnRegisterForm();
   RemoveSysButtons();
 }
 
 FWL_Type IFWL_Form::GetClassID() const {
   return FWL_Type::Form;
@@ skipping 555 matching lines @@
       HitTest(pMsg->m_fx, pMsg->m_fy) == FWL_WidgetHit::Titlebar) {
     if (m_bMaximized)
       SetWidgetRect(m_rtRestore);
     else
       SetWorkAreaRect();
 
     Update();
     m_bMaximized = !m_bMaximized;
   }
 }