Add baked-in favicons for default popular sites on NTP

components/ntp_tiles/icon_cacher_impl.h

Index: components/ntp_tiles/icon_cacher_impl.h
diff --git a/components/ntp_tiles/icon_cacher_impl.h b/components/ntp_tiles/icon_cacher_impl.h
index 1028f72b29b7153cdd64706eaa4bc3623de11b41..8e390a7af1d18e02e608c2a24e4eaf5781aae8ff 100644
--- a/components/ntp_tiles/icon_cacher_impl.h
+++ b/components/ntp_tiles/icon_cacher_impl.h
@@ -52,6 +52,9 @@ class IconCacherImpl : public IconCacher {
                            const std::string& id,
                            const gfx::Image& fetched_image);
 
+  bool ProvideDefaultIcon(const PopularSites::Site& site);
+  void SaveIconForSite(const PopularSites::Site& site, const gfx::Image image);
+
   base::CancelableTaskTracker tracker_;
   favicon::FaviconService* const favicon_service_;
   std::unique_ptr<image_fetcher::ImageFetcher> const image_fetcher_;