pub trait MessagePortProxyInterface: Send + Sync {
type PostMessageResponseFut: Future<Output = Result<MessagePortPostMessageResult, Error>> + Send;
type ReceiveMessageResponseFut: Future<Output = Result<WebMessage, Error>> + Send;
// Required methods
fn post_message(&self, message: WebMessage) -> Self::PostMessageResponseFut;
fn receive_message(&self) -> Self::ReceiveMessageResponseFut;
}