title: Mitmdump does not working with selenium-webDriver
body: <p>I use Selenium::WebDriver::Remote::Capabilities.chrome and chromeOptions with --proxy-server (mitmdump is used like proxy-server). But when I run the code and go to check ip, it's still mine.</p>
  
  <pre class="lang-rb prettyprint-override"><code>args = [
        "mitmdump",
        "--listen-host", "127.0.0.1",
        "--listen-port", @port,
        "--mode", "upstream:http://#{proxy.ip}:#{proxy.port}",
        "--upstream-auth", #{proxy.login}:#{proxy.password}
      ]
  
  server = ChildProcess.build(*args)
  server.start
  raise "Oops" unless server.alive?
  
  Capybara.register_driver :selenium do |app|
        caps = Selenium::WebDriver::Remote::Capabilities.chrome(
          "chromeOptions" =&gt; {
            "args" =&gt; [
              "--headless",
              "--proxy-server=http://127.0.0.1:@port",
              "--disable-dev-shm-usage",
              "--blink-settings=imagesEnabled=true",
              "window-size=1440,900",
              "--no-sandbox"
            ]
          }
        )
        Capybara::Selenium::Driver.new(app, browser: :chrome, desired_capabilities: caps)
      end
  
      Capybara.javascript_driver = :chrome
      Capybara.configure do |config|
        config.default_max_wait_time = 20
        config.default_driver = :selenium
      end
  
      session = Capybara::Session.new(:selenium)
  
      session.visit("https://www.2ip.ru")
  </code></pre>