async onLaunchApp(event) {
    Object.assign(this.context, {
      bundleId: event.bundleId,
      launchArgs: event.launchArgs,
      pid: event.pid,
   });
  }
Hook that is called inside device.launchApp() and
provides a new pid for the relaunched app for the
artifacts that are dependent on pid.

@protected
@async
@param {Object} event - Launch app event object
@param {string} event.deviceId - Current deviceId
@param {string} event.bundleId - Current bundleId
@param {Object} event.launchArgs - key-value pairs of launch args
@param {number} event.pid - Process id of the running app
@return {Promise<void>} - when done