[NTP Snippets] Schedule periodic fetching

ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc

Index: ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
diff --git a/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc b/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
index 0602d85c4d94e7ee3d2fdae22a19682ddb71fca4..319d1f898c4a47b1d9c3380645bb475190a1c34f 100644
--- a/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
+++ b/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
@@ -54,13 +54,15 @@ IOSChromeNTPSnippetsServiceFactory::BuildServiceInstanceFor(
   scoped_refptr<net::URLRequestContextGetter> request_context =
       browser_state->GetRequestContext();
 
+  ntp_snippets::NTPSnippetsScheduler* scheduler = nullptr;
+
   scoped_refptr<base::SequencedTaskRunner> task_runner =
       web::WebThread::GetBlockingPool()
           ->GetSequencedTaskRunnerWithShutdownBehavior(
               base::SequencedWorkerPool::GetSequenceToken(),
               base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
   return make_scoped_ptr(new ntp_snippets::NTPSnippetsService(
-      task_runner, GetApplicationContext()->GetApplicationLocale(),
+      task_runner, GetApplicationContext()->GetApplicationLocale(), scheduler,
       make_scoped_ptr(new ntp_snippets::NTPSnippetsFetcher(
           task_runner, (SigninManagerBase*)signin_manager, token_service,
           request_context, browser_state->GetStatePath()))));