Function set_network_conditions 

pub async fn set_network_conditions(
    client: &CdpClient,
    session_id: &str,
    offline: bool,
    latency_ms: f64,
    download_throughput: f64,
    upload_throughput: f64,
) -> Result<(), String>

Activate Network.emulateNetworkConditions (latency ms; throughput bytes/s, -1 = unlimited).