Files.app: Override overflow specifying to use the original scroll bar.

ui/file_manager/file_manager/foreground/css/file_manager.css

Index: ui/file_manager/file_manager/foreground/css/file_manager.css
diff --git a/ui/file_manager/file_manager/foreground/css/file_manager.css b/ui/file_manager/file_manager/foreground/css/file_manager.css
index 96eab73bc759a110562c0e5ac2f586d43ff13960..8059f171ff131482f32f4aeca2626efbd69fb02a 100644
--- a/ui/file_manager/file_manager/foreground/css/file_manager.css
+++ b/ui/file_manager/file_manager/foreground/css/file_manager.css
@@ -617,6 +617,12 @@ html[dir='rtl'] .breadcrumbs .separator {
   padding-bottom: 0;  /* For the preview panel. Will be overridden by JS. */
 }
 
+#file-list {
+  /* Override overflow specifying by table_list.js to use the original scroll
+     bar. crbug.com/391698 */
+  overflow: scroll !important;
+}
+
 #file-list .drag-selection-border {
   -webkit-box-sizing: border-box;
   background-color: rgba(255, 255, 255, 0.3);