MD Settings: Remove tabindex from container after it is blurred.

chrome/browser/resources/settings/settings_ui/settings_ui.js

Index: chrome/browser/resources/settings/settings_ui/settings_ui.js
diff --git a/chrome/browser/resources/settings/settings_ui/settings_ui.js b/chrome/browser/resources/settings/settings_ui/settings_ui.js
index f0d6c15b5b453db715dfa7dce258384d36af6cf3..e3e0e591127546aab2d508ae395a82046d913bd0 100644
--- a/chrome/browser/resources/settings/settings_ui/settings_ui.js
+++ b/chrome/browser/resources/settings/settings_ui/settings_ui.js
@@ -268,7 +268,13 @@ Polymer({
 
   /** @private */
   onMenuClosed_: function() {
+    // Add tab index so that the container can be focused.
+    this.$.container.setAttribute('tabindex', '-1');
     this.$.container.focus();
+
+    listenOnce(this.$.container, ['blur', 'pointerdown'], function() {
+      this.$.container.removeAttribute('tabindex');
+    }.bind(this));
   },
 
   /** @private */