Add SpecialListUsers::prefixSearchSubpages

This shows the existing user groups as subpages on search suggestion

Change-Id: I8c31c31d420287dd9d668186d1d5555488a9a3e9

includes/specials/SpecialListusers.php

@@ -399,6 +399,18 @@ class SpecialListUsers extends IncludableSpecialPage {
 		$this->getOutput()->addHTML( $s );
 	}
 
+	/**
+	 * Return an array of subpages beginning with $search that this special page will accept.
+	 *
+	 * @param string $search Prefix to search for
+	 * @param integer $limit Maximum number of results to return
+	 * @return string[] Matching subpages
+	 */
+	public function prefixSearchSubpages( $search, $limit = 10 ) {
+		$subpages = User::getAllGroups();
+		return self::prefixSearchArray( $search, $limit, $subpages );
+	}
+
 	protected function getGroupName() {
 		return 'users';
 	}