Function webkit2gtk_sys::webkit_web_view_send_message_to_page_finish

pub unsafe extern "C" fn webkit_web_view_send_message_to_page_finish(
    web_view: *mut WebKitWebView,
    result: *mut GAsyncResult,
    error: *mut *mut GError
) -> *mut WebKitUserMessage

Available on crate feature v2_28 only.