Remove old downloads UI; Material Design version is now the default.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index ff183c6040778e443e0448eefdffe81312f07e3d..3cfe1f7827e9e44c2d74b71ec9855aa57ac5609c 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -652,10 +652,6 @@ if (!is_android) {
     if (!enable_app_list) {
       sources -= [ "../browser/ui/webui/app_list/start_page_browsertest.js" ]
     }
-    if (!enable_supervised_users) {
-      sources -=
-          [ "../browser/ui/webui/downloads_ui_supervised_browsertest.js" ]
-    }
     if (!enable_print_preview) {
       sources -= [ "data/webui/print_preview.js" ]
     }