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

content/browser/net/quota_policy_cookie_store.cc

Index: content/browser/net/quota_policy_cookie_store.cc
diff --git a/content/browser/net/quota_policy_cookie_store.cc b/content/browser/net/quota_policy_cookie_store.cc
index dd3f35982cca13a61892d8cc1f2b16182ce6d4f8..438e1a06de947c58d57a959b8f99cc0ae06b15bf 100644
--- a/content/browser/net/quota_policy_cookie_store.cc
+++ b/content/browser/net/quota_policy_cookie_store.cc
@@ -155,7 +155,8 @@ std::unique_ptr<net::CookieStore> CreateCookieStore(
 
     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(