NTP: Fix metrics recording race condition

components/ntp_tiles/most_visited_sites.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 COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_
 #define COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 154 matching lines @@
 
   ~MostVisitedSites() override;
 
   // Does not take ownership of |observer|, which must outlive this object and
   // must not be null.
   void SetMostVisitedURLsObserver(Observer* observer, int num_sites);
 
   void AddOrRemoveBlacklistedUrl(const GURL& url, bool add_url);
   void RecordTileTypeMetrics(const std::vector<int>& tile_types,
                              const std::vector<int>& sources);
-  void RecordOpenedMostVisitedItem(int index, int tile_type);
+  void RecordOpenedMostVisitedItem(int index, int tile_type, int source);
 
   // MostVisitedSitesSupervisor::Observer implementation.
   void OnBlockedSitesChanged() override;
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
  private:
   friend class MostVisitedSitesTest;
 
   void BuildCurrentSuggestions();
@@ skipping 95 matching lines @@
 
   // For callbacks may be run after destruction.
   base::WeakPtrFactory<MostVisitedSites> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MostVisitedSites);
 };
 
 }  // namespace ntp_tiles
 
 #endif  // COMPONENTS_NTP_TILES_MOST_VISITED_SITES_H_