Files.app: Make DialogFooter UI class.

ui/file_manager/file_manager/main.html

Index: ui/file_manager/file_manager/main.html
diff --git a/ui/file_manager/file_manager/main.html b/ui/file_manager/file_manager/main.html
index fa6d025cf2550b672a34435d0b56c995d1767e54..01977de7d83e71d54c5b41a6a044ff4b94db31c0 100644
--- a/ui/file_manager/file_manager/main.html
+++ b/ui/file_manager/file_manager/main.html
@@ -112,6 +112,7 @@
       <script src="foreground/js/thumbnail_loader.js"></script>
       <script src="foreground/js/ui/conflict_dialog.js"></script>
       <script src="foreground/js/ui/default_action_dialog.js"></script>
+      <script src="foreground/js/ui/dialog_footer.js"></script>
       <script src="foreground/js/ui/directory_tree.js"></script>
       <script src="foreground/js/ui/drag_selector.js"></script>
       <script src="foreground/js/ui/drive_banners.js"></script>