fixup! TB 3455: Add DomainIsolator, for isolating circuit by domain.

const CLEAR_TIMEOUT = 600_000;

/**

 * @typedef {string} CircuitId A string that we use to identify a circuit.

 * Currently, it is a string that combines SOCKS credentials, to make it easier

 * to use as a map key.

 * It is not related to Tor's CircuitIDs.

 * @typedef {string} IsolationKey A string that we use to identify an isolation

 * key. Currently, it is a string that combines SOCKS credentials.

 * Each isolation key is used to identify a set of circuits.

 */

/**

 * @typedef {number} BrowserId

/**

 * @typedef BrowserCircuits Circuits related to a certain combination of

 * isolators (first-party domain and user context ID, currently).

 * @property {CircuitId} current The id of the last known circuit that has been

 * used to fetch data for the isolated context.

 * @property {CircuitId?} pending The id of the last used circuit for this

 * isolation context. We might or might not know data about it, yet. But if we

 * know it, we should move this id into current.

 * @property {IsolationKey} current The last isolation key for which circuit

 * information is known.

 * @property {IsolationKey?} pending The last used isolation key.

 * We might or might not know data about it, yet. But if we know it, we should

 * move this key into current, and pending should be made null.

 */

/**

  #catchallDirtySince = Date.now();

  /**

   * A map that associates circuit ids to the circuit information.

   * A map that associates an isolation context to its circuits.

   *

   * @type {Map<CircuitId, CircuitData>}

   * @type {Map<IsolationKey, CircuitData>}

   */

  #knownCircuits = new Map();

   *

   * @param {string} username The SOCKS username

   * @param {string} password The SOCKS password

   * @returns {CircuitId} A string that combines username and password and can

   * be used for map lookups.

   * @returns {IsolationKey} A string that combines username and password and

   * can be used as a key for maps.

   */

  #credentialsToId(username, password) {

  #credentialsToKey(username, password) {

    return `${username}|${password}`;

  }

      this.#browsers.set(browser.browserId, browserCircuits);

    }

    const circuitIds = browserCircuits.get(username) ?? {};

    const id = this.#credentialsToId(username, password);

    const id = this.#credentialsToKey(username, password);

    if (circuitIds.current === id) {

      // The circuit with these credentials was already built (we already knew

      // its nodes, or we would not have promoted it to the current circuit).

   * compose the circuit

   */

  async #updateCircuit(username, password, circuit) {

    const id = this.#credentialsToId(username, password);

    let data = this.#knownCircuits.get(id) ?? [];

    const key = this.#credentialsToKey(username, password);

    let data = this.#knownCircuits.get(key) ?? [];

    // Should we modify the lower layer to send a circuit identifier, instead?

    if (

      circuit.length === data.length &&