Make NTPTile copyable.

components/ntp_tiles/ntp_tile.cc

Index: components/ntp_tiles/ntp_tile.cc
diff --git a/components/ntp_tiles/ntp_tile.cc b/components/ntp_tiles/ntp_tile.cc
index 82d16ce450f808b380c5f4f90ecb522e55bdc149..df91380f3f59922217779f1e3e39eadceb0f0b70 100644
--- a/components/ntp_tiles/ntp_tile.cc
+++ b/components/ntp_tiles/ntp_tile.cc
@@ -14,4 +14,13 @@ NTPTile::NTPTile(NTPTile&&) = default;
 
 NTPTile& NTPTile::operator=(NTPTile&&) = default;
 
+NTPTile NTPTile::Copy() const {
+  NTPTile copy;
+  copy.title = title;
+  copy.url = url;
+  copy.source = source;
+  copy.whitelist_icon_path = whitelist_icon_path;
+  return copy;
+}
+
 }  // namespace ntp_tiles