urlStr := uu.String()
	u, err := url.Parse(urlStr)
	if err != nil {
		// Mark offline, with no reconnection attempts.
		connected = int32(offline)
		err = &url.Error{URL: urlStr, Err: err}
	}
	// The host's colon:port should be normalized. See Issue 14836.
	u.Host = removeEmptyPort(u.Host)

	// Transport is exactly same as Go default in https://golang.org/pkg/net/http/#RoundTripper
	// except custom DialContext and TLSClientConfig.