MD Settings: Bluetooth: Add error dialog and messages

ui/webui/resources/js/i18n_behavior.js

Index: ui/webui/resources/js/i18n_behavior.js
diff --git a/ui/webui/resources/js/i18n_behavior.js b/ui/webui/resources/js/i18n_behavior.js
index f8c97ad6bdf4b42cd061d1bc152234d248933d36..56428c9b7e3ec3024506ff9424134f0bf82bee34 100644
--- a/ui/webui/resources/js/i18n_behavior.js
+++ b/ui/webui/resources/js/i18n_behavior.js
@@ -57,4 +57,13 @@ var I18nBehavior = {
     return parseHtmlSubset('<b>' + rawString + '</b>', opts.tags, opts.attrs)
         .firstChild.innerHTML;
   },
+
+  /**
+   * Returns true if a translation exists for |id|.
+   * @param {string} id
+   * @return {boolean}
+   */
+  i18nExists: function(id) {
+    return loadTimeData.valueExists(id);
+  },
 };