Settings WebUI: password export dialog, send close event after any open dialog is removed from dom

Bug: 910488
Change-Id: I566c42a2a6141d963b538208a400b38fcdc64e4e
Reviewed-on: https://chromium-review.googlesource.com/c/1359292
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613386}

chrome/browser/resources/settings/autofill_page/passwords_export_dialog.js

@@ -171,7 +171,9 @@ Polymer({
     this.showStartDialog_ = false;
     this.showProgressDialog_ = false;
     this.showErrorDialog_ = false;
-    this.fire('passwords-export-dialog-close');
+    // Need to allow for the dialogs to be removed from the DOM before firing
+    // the close event. Otherwise the handler will not be able to set focus.
+    this.async(() => this.fire('passwords-export-dialog-close'));
   },
 
   /**