Watch destruction of widgets around OnAAction() method

fpdfsdk/formfiller/cffl_formfiller.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 "fpdfsdk/formfiller/cffl_formfiller.h"
 
 #include "core/fpdfapi/fpdf_page/include/cpdf_page.h"
 #include "core/fxge/include/cfx_renderdevice.h"
@@ skipping 509 matching lines @@
   return rect;
 }
 
 FX_BOOL CFFL_FormFiller::CommitData(CPDFSDK_PageView* pPageView,
                                     uint32_t nFlag) {
   if (IsDataChanged(pPageView)) {
     FX_BOOL bRC = TRUE;
     FX_BOOL bExit = FALSE;
     CFFL_InteractiveFormFiller* pFormFiller =
         m_pEnv->GetInteractiveFormFiller();
-    pFormFiller->OnKeyStrokeCommit(m_pWidget, pPageView, bRC, bExit, nFlag);
-    if (bExit)
+    CPDFSDK_Annot::ObservedPtr pObserved(m_pWidget);
+    pFormFiller->OnKeyStrokeCommit(&pObserved, pPageView, bRC, bExit, nFlag);
+    if (!pObserved || bExit)
       return TRUE;
     if (!bRC) {
       ResetPDFWindow(pPageView, FALSE);
       return TRUE;
     }
-
-    pFormFiller->OnValidate(m_pWidget, pPageView, bRC, bExit, nFlag);
-    if (bExit)
+    pFormFiller->OnValidate(&pObserved, pPageView, bRC, bExit, nFlag);
+    if (!pObserved || bExit)
       return TRUE;
     if (!bRC) {
       ResetPDFWindow(pPageView, FALSE);
       return TRUE;
     }
-
     SaveData(pPageView);
     pFormFiller->OnCalculate(m_pWidget, pPageView, bExit, nFlag);
     if (bExit)
       return TRUE;
 
     pFormFiller->OnFormat(m_pWidget, pPageView, bExit, nFlag);
   }
   return TRUE;
 }
 
@@ skipping 156 matching lines @@
     pWidget->DrawAppearance(pDevice, pUser2Device, CPDF_Annot::Normal, nullptr);
   }
 }
 
 void CFFL_Button::OnDrawDeactive(CPDFSDK_PageView* pPageView,
                                  CPDFSDK_Annot* pAnnot,
                                  CFX_RenderDevice* pDevice,
                                  CFX_Matrix* pUser2Device) {
   OnDraw(pPageView, pAnnot, pDevice, pUser2Device);
 }