/**
 * Websocket server for handling browser activity
 *
 * Watches the browser tab to notify if tab is closed or user leaves page app.
 *   1) Launch server to listen for incoming websocket connections
 *   2) For each connection,
 *   3) ... listen for introduction message that has connectionId, capture it
 *   4) ... attach close handler passing connectionId.
 */
export declare class BrowserWatcher {
    start(port: number): Promise<void>;
}