WP_Customize_Manager::remove_frameless_preview_messenger_channel PHP Method

    public function remove_frameless_preview_messenger_channel()
    {
        if (!$this->messenger_channel) {
            return;
        }
        ?>
		<script>
		( function() {
			var urlParser, oldQueryParams, newQueryParams, i;
			if ( parent !== window ) {
				return;
			}
			urlParser = document.createElement( 'a' );
			urlParser.href = location.href;
			oldQueryParams = urlParser.search.substr( 1 ).split( /&/ );
			newQueryParams = [];
			for ( i = 0; i < oldQueryParams.length; i += 1 ) {
				if ( ! /^customize_messenger_channel=/.test( oldQueryParams[ i ] ) ) {
					newQueryParams.push( oldQueryParams[ i ] );
				}
			}
			urlParser.search = newQueryParams.join( '&' );
			if ( urlParser.search !== location.search ) {
				location.replace( urlParser.href );
			}
		} )();
		</script>
		<?php 
    }

 /**
  * Test remove_frameless_preview_messenger_channel.
  *
  * @ticket 38867
  * @covers WP_Customize_Manager::remove_frameless_preview_messenger_channel()
  */
 function test_remove_frameless_preview_messenger_channel()
 {
     wp_set_current_user(self::$admin_user_id);
     $manager = new WP_Customize_Manager(array('messenger_channel' => null));
     ob_start();
     $manager->remove_frameless_preview_messenger_channel();
     $output = ob_get_clean();
     $this->assertEmpty($output);
     $manager = new WP_Customize_Manager(array('messenger_channel' => 'preview-0'));
     ob_start();
     $manager->remove_frameless_preview_messenger_channel();
     $output = ob_get_clean();
     $this->assertContains('<script>', $output);
 }