[NTP Snippets] Schedule periodic fetching

components/ntp_snippets/ntp_snippets_fetcher.h

 // Copyright 2016 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
 
 #include "base/callback.h"
 #include "base/callback_list.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 63 matching lines @@
   scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
 
   // Holds the URL request context. Not owned.
   net::URLRequestContextGetter* url_request_context_getter_;
 
   scoped_ptr<net::URLFetcher> url_fetcher_;
   scoped_ptr<SigninManager> signin_manager_;
   scoped_ptr<OAuth2TokenService> token_service_;
   scoped_ptr<OAuth2TokenService::Request> oauth_request_;
 
+  bool waiting_for_refresh_token_;
+
   SnippetsAvailableCallbackList callback_list_;
 
   base::WeakPtrFactory<NTPSnippetsFetcher> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsFetcher);
 };
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_