Ensure PopularSite icon availability in ntp_tiles.

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 28f9b070df0a6421fec0400df63b023a84af57ec..9d8318af79a7461c8a025d7690fb3416cf36e65e 100644
--- a/components/ntp_tiles/most_visited_sites.h
+++ b/components/ntp_tiles/most_visited_sites.h
@@ -34,6 +34,8 @@ class PrefRegistrySyncable;
 
 namespace ntp_tiles {
 
+class IconCacher;
+
 // Shim interface for SupervisedUserService.
 class MostVisitedSitesSupervisor {
  public:
@@ -105,7 +107,8 @@ class MostVisitedSites : public history::TopSitesObserver,
   class Observer {
    public:
     virtual void OnMostVisitedURLsAvailable(const NTPTilesVector& tiles) = 0;
-    virtual void OnPopularURLsAvailable(const PopularSitesVector& sites) {}
+    // TODO(sfiera): make this method required after iOS implements it:
+    virtual void OnIconMadeAvailable(const GURL& site_url) {}
 
    protected:
     virtual ~Observer() {}
@@ -120,6 +123,7 @@ class MostVisitedSites : public history::TopSitesObserver,
                    scoped_refptr<history::TopSites> top_sites,
                    suggestions::SuggestionsService* suggestions,
                    std::unique_ptr<PopularSites> popular_sites,
+                   std::unique_ptr<IconCacher> icon_cacher,
                    MostVisitedSitesSupervisor* supervisor);
 
   ~MostVisitedSites() override;
@@ -186,6 +190,8 @@ class MostVisitedSites : public history::TopSitesObserver,
 
   void OnPopularSitesAvailable(bool success);
 
+  void OnIconMadeAvailable(const GURL& site_url, bool newly_available);
+
   // Records UMA histogram metrics related to the number of impressions.
   void RecordImpressionUMAMetrics();
 
@@ -198,6 +204,7 @@ class MostVisitedSites : public history::TopSitesObserver,
   scoped_refptr<history::TopSites> top_sites_;
   suggestions::SuggestionsService* suggestions_service_;
   std::unique_ptr<PopularSites> const popular_sites_;
+  std::unique_ptr<IconCacher> const icon_cacher_;
   MostVisitedSitesSupervisor* supervisor_;
 
   Observer* observer_;