Switch out WordPress Search for Google Domain Search

wp-google-search.php

if ( ! function_exists( 'google_search_form' ) ) :

function google_search_form( $form ) {
   $form  = '<form method="get" action="http://www.google.com/search" class="search">';
   $form .= '<input type="hidden" name="domains" value="' . get_bloginfo('url') . '">';
   $form .= '<input type="hidden" name="sitesearch" value="' . get_bloginfo('url') . '">';
   $form .= '<input type="text" name="q" placeholder="Search" class="input">';
   $form .= '<input type="submit" value="Submit" class="submit">';
   $form .= '</form>';
 return $form;
}

add_filter('get_search_form','google_search_form');

endif;