To reproduce crashes of JSONPrefStore

chrome/browser/profiles/profile_io_data.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/profiles/profile_io_data.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 1290 matching lines @@
     net::ChannelIDService* channel_id_service) const {
   channel_id_service_.reset(channel_id_service);
 }
 
 void ProfileIOData::DestroyResourceContext() {
   resource_context_.reset();
   // Prevent the cert_transparency_observer_ from getting any more
   // notifications by severing the link between it and the
   // cert_transparency_verifier_ and unregistering it from new STH
   // notifications.
-  cert_transparency_verifier_->SetObserver(nullptr);
-  ct_tree_tracker_unregistration_.Run();
+  if (cert_transparency_verifier_)
+    cert_transparency_verifier_->SetObserver(nullptr);
+  if (!ct_tree_tracker_unregistration_.is_null())
+    ct_tree_tracker_unregistration_.Run();
 }
 
 std::unique_ptr<net::HttpNetworkSession>
 ProfileIOData::CreateHttpNetworkSession(
     const ProfileParams& profile_params) const {
   net::URLRequestContext* context = main_request_context();
 
   IOThread* const io_thread = profile_params.io_thread;
 
   net::HttpNetworkSession::Params params(io_thread->NetworkSessionParams());
@@ skipping 32 matching lines @@
 void ProfileIOData::SetCookieSettingsForTesting(
     content_settings::CookieSettings* cookie_settings) {
   DCHECK(!cookie_settings_.get());
   cookie_settings_ = cookie_settings;
 }
 
 policy::URLBlacklist::URLBlacklistState ProfileIOData::GetURLBlacklistState(
     const GURL& url) const {
   return url_blacklist_manager_->GetURLBlacklistState(url);
 }