[Suggestions Service] Add support for expiring the SuggestionsStore

components/suggestions/suggestions_store.h

 // Copyright 2014 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_SUGGESTIONS_SUGGESTIONS_STORE_H_
 #define COMPONENTS_SUGGESTIONS_SUGGESTIONS_STORE_H_
 
 #include "base/macros.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 
@@ skipping 30 matching lines @@
 
  protected:
   // Test seam. For simplicity of mock creation.
   SuggestionsStore() {}
 
  private:
   // The pref service used to persist the suggestions data.
   PrefService* pref_service_;
 
   DISALLOW_COPY_AND_ASSIGN(SuggestionsStore);
+
+  // Filters expired suggestions.
+  void FilterExpiredSuggestions(SuggestionsProfile* suggestions);
 };
 
 }  // namespace suggestions
 
 #endif  // COMPONENTS_SUGGESTIONS_SUGGESTIONS_STORE_H_