get_preview_url example

'changesetAutoSave'       => AUTOSAVE_INTERVAL * 1000,
                'keepAliveCheck'          => 2500,
                'reflowPaneContents'      => 100,
                'previewFrameSensitivity' => 2000,
            ),
            'theme'                  => array(
                'stylesheet'  => $this->get_stylesheet(),
                'active'      => $this->is_theme_active(),
                '_canInstall' => current_user_can( 'install_themes' ),
            ),
            'url'                    => array(
                'preview'       => sanitize_url( $this->get_preview_url() ),
                'return'        => sanitize_url( $this->get_return_url() ),
                'parent'        => sanitize_url( admin_url() ),
                'activated'     => sanitize_url( home_url( '/' ) ),
                'ajax'          => sanitize_url( admin_url( 'admin-ajax.php', 'relative' ) ),
                'allowed'       => array_map( 'sanitize_url', $this->get_allowed_urls() ),
                'isCrossDomain' => $this->is_cross_domain(),
                'home'          => sanitize_url( home_url( '/' ) ),
                'login'         => sanitize_url( $login_url ),
            ),
            'browser'                => array(
                'mobile' => wp_is_mobile(),