def stop
    return self unless running?
    if @pid
      begin
        ::Process.kill 'TERM', @pid
        ::Process.wait @pid
      rescue SystemCallError
        # Process died on its own.
      ensure
        @pid = nil
      end
    end

    FileUtils.rm_rf @data_dir if File.exist?(@data_dir)
    @running = false
    self
  end
def stop
    return self unless running?
    if @pid
      begin
        ::Process.kill 'TERM', @pid
        ::Process.wait @pid
      rescue SystemCallError
        # Process died on its own.
      ensure
        @pid = nil
      end
    end

    FileUtils.rm_rf @data_dir if File.exist?(@data_dir)
    @running = false
    self
  end
Stops the browser process.

 Only call this after you're done with the process.

 @return [WebkitRemote::Process] self