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..6854daefa5b73d1d94e5f37287656e7e56570e1d 100644
--- a/components/ntp_tiles/icon_cacher_impl.h
+++ b/components/ntp_tiles/icon_cacher_impl.h
@@ -39,19 +39,22 @@ class IconCacherImpl : public IconCacher {
   ~IconCacherImpl() override;
 
   void StartFetch(PopularSites::Site site,
-                  const base::Callback<void(bool)>& done) override;
+                  const base::Callback<void()>& icon_available) override;
 
  private:
   void OnGetFaviconImageForPageURLFinished(
       PopularSites::Site site,
-      const base::Callback<void(bool)>& done,
+      const base::Callback<void()>& done,
       const favicon_base::FaviconImageResult& result);
 
   void OnFaviconDownloaded(PopularSites::Site site,
-                           const base::Callback<void(bool)>& done,
+                           const base::Callback<void()>& done,
                            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_;