[Popular Sites] Add Variations parameter to override URL path

components/ntp_tiles/popular_sites_impl.h

Index: components/ntp_tiles/popular_sites_impl.h
diff --git a/components/ntp_tiles/popular_sites_impl.h b/components/ntp_tiles/popular_sites_impl.h
index 1f0fbbe6b1ce90e867f74f36d7a4ad3eac12c997..b045dea6a7994c0adc70e21de9283115b6a7600c 100644
--- a/components/ntp_tiles/popular_sites_impl.h
+++ b/components/ntp_tiles/popular_sites_impl.h
@@ -67,6 +67,7 @@ class PopularSitesImpl : public PopularSites, public net::URLFetcherDelegate {
   const SitesVector& sites() const override;
   GURL GetLastURLFetched() const override;
   GURL GetURLToFetch() override;
+  std::string GetDirectoryToFetch() override;
   std::string GetCountryToFetch() override;
   std::string GetVersionToFetch() override;
   const base::ListValue* GetCachedJson() override;