Use TaskShutdownBehavior::BLOCK_SHUTDOWN in content::CreateCookieStore().

content/browser/net/quota_policy_cookie_store.cc

 // Copyright 2015 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 "content/browser/net/quota_policy_cookie_store.h"
 
 #include <list>
 #include <memory>
 
 #include "base/bind.h"
@@ skipping 137 matching lines @@
     scoped_refptr<base::SequencedTaskRunner> background_task_runner =
         config.background_task_runner;
 
     if (!client_task_runner.get()) {
       client_task_runner =
           BrowserThread::GetTaskRunnerForThread(BrowserThread::IO);
     }
 
     if (!background_task_runner.get()) {
       background_task_runner = base::CreateSequencedTaskRunnerWithTraits(
-          {base::MayBlock(), base::TaskPriority::BACKGROUND});
+          {base::MayBlock(), base::TaskPriority::BACKGROUND,
+           base::TaskShutdownBehavior::BLOCK_SHUTDOWN});
     }
 
     scoped_refptr<net::SQLitePersistentCookieStore> sqlite_store(
         new net::SQLitePersistentCookieStore(
             config.path,
             client_task_runner,
             background_task_runner,
             (config.session_cookie_mode ==
              CookieStoreConfig::RESTORED_SESSION_COOKIES),
             config.crypto_delegate));
@@ skipping 13 matching lines @@
     }
   }
 
   if (!config.cookieable_schemes.empty())
     cookie_monster->SetCookieableSchemes(config.cookieable_schemes);
 
   return std::move(cookie_monster);
 }
 
 }  // namespace content