Add WP_login merge tag to gravity forms

gravity_merge_tags.php

<?php

class extraGravityMergeTags
{

function __construct()
{
  	add_filter( 'gform_custom_merge_tags', array( $this, 'add_merge_tags' ), 10, 4 );
	add_filter( 'gform_replace_merge_tags', array( $this, 'run_merge_tags' ) , 10, 7);
}

function add_merge_tags($merge_tags, $form_id, $fields, $element_id) 
{    
	$merge_tags[] = array( 'label' => 'WordPress Login URL', 'tag' => '{wp_login}' );	    
	return $merge_tags;
}


function run_merge_tags($text, $form, $entry, $url_encode, $esc_html, $nl2br, $format) 
{   
	$custom_merge_tag = '{wp_login}';
	
	if( strpos( $text, $custom_merge_tag ) === false )
		return $text;
	    
	$login_link = get_bloginfo( 'url' ) . '/login/';
	$text = str_replace( $custom_merge_tag, $login_link, $text );
	    
	return $text;
}

}

new extraGravityMergeTags();