cr-network-select: implement focus()

ui/webui/resources/cr_elements/network/cr_network_select.js

Index: ui/webui/resources/cr_elements/network/cr_network_select.js
diff --git a/ui/webui/resources/cr_elements/network/cr_network_select.js b/ui/webui/resources/cr_elements/network/cr_network_select.js
index eb1efea6ff96afc8e5c0caa47e6b8dfff34867da..0349141de907255b289c059667ceb1e981297489 100644
--- a/ui/webui/resources/cr_elements/network/cr_network_select.js
+++ b/ui/webui/resources/cr_elements/network/cr_network_select.js
@@ -56,6 +56,10 @@ Polymer({
     },
   },
 
+  focus: function() {
+    this.$.networkList.focus();
+  },
+
   /**
    * Listener function for chrome.networkingPrivate.onNetworkListChanged event.
    * @type {function(!Array<string>)}