SuggestionsService: implement SyncServiceObserver

chrome/browser/search/instant_service.h

 // Copyright 2013 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 CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_
 #define CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_
 
 #include <set>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/top_sites_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/search_engines/template_url_service_observer.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 #include "components/suggestions/suggestions_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
@@ skipping 154 matching lines @@
   scoped_ptr<InstantSearchPrerenderer> instant_prerenderer_;
 
   // Used to check whether notifications from TemplateURLService indicate a
   // change that affects the default search provider.
   scoped_ptr<TemplateURLData> previous_default_search_provider_;
   GURL previous_google_base_url_;
 
   // Suggestions Service to fetch server suggestions.
   suggestions::SuggestionsService* suggestions_service_;
 
+  // Subscription to the SuggestionsService.
+  scoped_ptr<
+      suggestions::SuggestionsService::ResponseCallbackList::Subscription>
+      suggestions_subscription_;
+
   // Used for Top Sites async retrieval.
   base::WeakPtrFactory<InstantService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InstantService);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_