[autofill] Fix crash while closing tab or browser window with interactive

chrome/browser/autofill/autofill_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/autofill/autofill_manager.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <map>
@@ skipping 761 matching lines @@
   base::Callback<void(const FormStructure*)> callback =
       base::Bind(&AutofillManager::ReturnAutocompleteData, this);
   autofill::AutofillDialogController* controller =
       new autofill::AutofillDialogController(web_contents(),
                                              form,
                                              callback);
   controller->Show();
 }
 
 void AutofillManager::ReturnAutocompleteData(const FormStructure* result) {
+  // web_contents() will be NULL when the interactive autocomplete is closed due
+  // to a tab or browser window closing.
+  if (!web_contents())
+    return;
+
   RenderViewHost* host = web_contents()->GetRenderViewHost();
   if (!host)
     return;
 
   if (!result) {
     host->Send(new AutofillMsg_RequestAutocompleteFinished(
         host->GetRoutingID(), WebKit::WebFormElement::AutocompleteResultError));
   } else {
     // TODO(estade): implement non-failure case.
     host->Send(new AutofillMsg_RequestAutocompleteFinished(
@@ skipping 522 matching lines @@
   *profile_guid = IDToGUID(profile_id);
 }
 
 void AutofillManager::UpdateInitialInteractionTimestamp(
     const TimeTicks& interaction_timestamp) {
   if (initial_interaction_timestamp_.is_null() ||
       interaction_timestamp < initial_interaction_timestamp_) {
     initial_interaction_timestamp_ = interaction_timestamp;
   }
 }