Do not check pointers before deleting them.

xfa/fwl/core/fwl_formimp.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/fwl_formimp.h"
 
 #include "xfa/fde/tto/fde_textout.h"
 #include "xfa/fwl/basewidget/fwl_formproxyimp.h"
@@ skipping 453 matching lines @@
   if (!pWidgetMgr)
     return;
   IFWL_Widget* pChild =
       pWidgetMgr->GetWidget(pParent, FWL_WGTRELATION_FirstChild);
   while (pChild) {
     pWidgetMgr->ShowWidget_Native(pChild);
     ShowChildWidget(pChild);
     pChild = pWidgetMgr->GetWidget(pChild, FWL_WGTRELATION_NextSibling);
   }
 }
+
 void CFWL_FormImp::RemoveSysButtons() {
   m_rtCaption.Reset();
-  if (m_pCloseBox) {
-    delete m_pCloseBox;
-    m_pCloseBox = NULL;
-  }
-  if (m_pMinBox) {
-    delete m_pMinBox;
-    m_pMinBox = NULL;
-  }
-  if (m_pMaxBox) {
-    delete m_pMaxBox;
-    m_pMaxBox = NULL;
-  }
-  if (m_pCaptionBox) {
-    delete m_pCaptionBox;
-    m_pCaptionBox = NULL;
-  }
+  delete m_pCloseBox;
+  m_pCloseBox = nullptr;
+  delete m_pMinBox;
+  m_pMinBox = nullptr;
+  delete m_pMaxBox;
+  m_pMaxBox = nullptr;
+  delete m_pCaptionBox;
+  m_pCaptionBox = nullptr;
 }
+
 void CFWL_FormImp::CalcContentRect(CFX_RectF& rtContent) {
 #ifdef FWL_UseMacSystemBorder
   rtContent = m_rtRelative;
 #else
   GetEdgeRect(rtContent);
   if (HasEdge()) {
     FX_FLOAT fEdge = GetEdgeWidth();
     rtContent.Deflate(fEdge, fEdge);
   }
 #endif
@@ skipping 655 matching lines @@
 }
 void CFWL_FormImpDelegate::OnWindowMove(CFWL_MsgWindowMove* pMsg) {
   m_pOwner->m_pProperties->m_rtWidget.left = pMsg->m_fx;
   m_pOwner->m_pProperties->m_rtWidget.top = pMsg->m_fy;
 }
 void CFWL_FormImpDelegate::OnClose(CFWL_MsgClose* pMsg) {
   CFWL_EvtClose eClose;
   eClose.m_pSrcTarget = m_pOwner->m_pInterface;
   m_pOwner->DispatchEvent(&eClose);
 }