{
    this._serviceWorkerRegistrationFronts.push(front);
    front.on("push-subscription-modified", this._listener);
    front.on("registration-changed", this._listener);
  }

  _onServiceWorkerRegistrationDestroyed(front) {
    this._serviceWorkerRegistrationFronts =
      this._serviceWorkerRegistrationFronts.filter(f => f !== front);
  }

  _onProcessDescriptorAvailable(processFront) {
    this._processDescriptors.push(processFront);
    processFront.watchFronts(
      "contentProcessTarget",
      this._onContentProcessTargetAvailable,
      this._onContentProcessTargetDestroyed
    );
  }

  _onProcessDescriptorDestroyed(processFront) {
    this._processDescriptors = this._processDescriptors.filter(
      f => f !== processFront
    );
  }
}

exports.WorkersListener = WorkersListener;
PK