pub unsafe extern "C" fn webkit_website_data_manager_clear(
    manager: *mut WebKitWebsiteDataManager,
    types: WebKitWebsiteDataTypes,
    timespan: GTimeSpan,
    cancellable: *mut GCancellable,
    callback: GAsyncReadyCallback,
    user_data: gpointer
)
Available on crate feature v2_16 only.