[Popular Sites] Add Variations parameter to override URL path

components/ntp_tiles/popular_sites_impl.h

 // Copyright 2016 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_POPULAR_SITES_IMPL_H_
 #define COMPONENTS_NTP_TILES_POPULAR_SITES_IMPL_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 49 matching lines @@
       ParseJSONCallback parse_json);
 
   ~PopularSitesImpl() override;
 
   // PopularSites implementation.
   bool MaybeStartFetch(bool force_download,
                        const FinishedCallback& callback) override;
   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;
 
   // Register preferences used by this class.
   static void RegisterProfilePrefs(
       user_prefs::PrefRegistrySyncable* user_prefs);
 
  private:
   // Fetch the popular sites at the given URL, overwriting any cache in prefs
@@ skipping 24 matching lines @@
   GURL pending_url_;
 
   base::WeakPtrFactory<PopularSitesImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PopularSitesImpl);
 };
 
 }  // namespace ntp_tiles
 
 #endif  // COMPONENTS_NTP_TILES_POPULAR_SITES_IMPL_H_