class Selenium::WebDriver::ChildProcess

def stop(timeout = 3)
  return unless @pid
  return if exited?
  terminate_and_wait_else_kill(timeout)
rescue Errno::ECHILD, Errno::ESRCH => e
  # Process exited earlier than terminate/kill could catch
  WebDriver.logger.debug("    -> process: #{@pid} does not exist (#{e.class.name})", id: :process)
end