Compile most of file_manager/background scripts in v2.

ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js

Index: ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js
diff --git a/ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js b/ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js
index b92a5d7cc425afba75c12ce21f8482e42cd55297..6d498d989998cd154077f0eebf2762ea5bcc1e7f 100644
--- a/ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js
+++ b/ui/file_manager/file_manager/foreground/js/ui/progress_center_panel.js
@@ -246,6 +246,7 @@ function ProgressCenterPanel(element) {
   /**
    * Callback to be called with the ID of the progress item when the cancel
    * button is clicked.
+   * @type {?function(string)}
    */
   this.cancelCallback = null;