[NTP Tiles] Fetch missing MostLikely tiles from a Google server

components/favicon_base/favicon_types.h

Index: components/favicon_base/favicon_types.h
diff --git a/components/favicon_base/favicon_types.h b/components/favicon_base/favicon_types.h
index 47c63aeb6fa0aca7d02999e5c5db8b622e90b4bc..2b2ecec2351177ee624f7f11c6f4f3fde553f391 100644
--- a/components/favicon_base/favicon_types.h
+++ b/components/favicon_base/favicon_types.h
@@ -90,6 +90,10 @@ struct LargeIconResult {
 
   ~LargeIconResult();
 
+  // Returns true if the LargeIconResult contains no data (neither in |bitmap|,
+  // nor in |fallback_icon_style|).
+  bool is_empty() const;
+
   // The bitmap from the favicon database if the database has a sufficiently
   // large one.
   FaviconRawBitmapResult bitmap;