Add baked-in favicons for default popular sites on NTP

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..47b06b612e09e1cd76c0b57143e926095d27e6b0 100644
--- a/components/ntp_tiles/popular_sites_impl.h
+++ b/components/ntp_tiles/popular_sites_impl.h
@@ -41,6 +41,8 @@ class TemplateURLService;
 
 namespace ntp_tiles {
 
+class IconCacher;
+
 using ParseJSONCallback = base::Callback<void(
     const std::string& unsafe_json,
     const base::Callback<void(std::unique_ptr<base::Value>)>& success_callback,
@@ -74,6 +76,9 @@ class PopularSitesImpl : public PopularSites, public net::URLFetcherDelegate {
   // Register preferences used by this class.
   static void RegisterProfilePrefs(
       user_prefs::PrefRegistrySyncable* user_prefs);
+  // Adds icon resources for default sites in prefs to cache.
+  static void AddIconsForDefaultPagesToCacher(const PrefService& prefs,
+                                              IconCacher* cacher);
 
  private:
   // Fetch the popular sites at the given URL, overwriting any cache in prefs