Pass PopularSites ownership to MostVisitedSites.

components/ntp_tiles/most_visited_sites.h

Index: components/ntp_tiles/most_visited_sites.h
diff --git a/components/ntp_tiles/most_visited_sites.h b/components/ntp_tiles/most_visited_sites.h
index 77440f4f2a9577ac948d22580dd9e43960dbb06b..58d327fd314d1e9e976d2d78c02d8073d407e9ed 100644
--- a/components/ntp_tiles/most_visited_sites.h
+++ b/components/ntp_tiles/most_visited_sites.h
@@ -119,7 +119,7 @@ class MostVisitedSites : public history::TopSitesObserver,
   MostVisitedSites(PrefService* prefs,
                    scoped_refptr<history::TopSites> top_sites,
                    suggestions::SuggestionsService* suggestions,
-                   PopularSites* popular_sites,
+                   std::unique_ptr<PopularSites> popular_sites,
                    MostVisitedSitesSupervisor* supervisor);
 
   ~MostVisitedSites() override;
@@ -195,7 +195,7 @@ class MostVisitedSites : public history::TopSitesObserver,
   PrefService* prefs_;
   scoped_refptr<history::TopSites> top_sites_;
   suggestions::SuggestionsService* suggestions_service_;
-  PopularSites* const popular_sites_;
+  std::unique_ptr<PopularSites> const popular_sites_;
   MostVisitedSitesSupervisor* supervisor_;
 
   Observer* observer_;