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### Issue Details

* **Electron Version:**
  8.0.1
* **Operating System:**
  macOS 10.14.6

### Expected Behavior
Send a request with `referer` header. It's worked with Node's `http/https` module, but failed when I change to `net.request`.

### Actual Behavior
No referer header

### To Reproduce
```js
ses.protocol.interceptStreamProtocol("https", (request, callback) => {
	const resp = sendRequestWithNetRequest({
       url: request.url,
       method: request.method,
	   headers: {
			...request.headers,
			referer: request.referrer  // only referrer has been ignored!!
       }
    })
    callback({
        data: resp.body,
        statusCode: resp.statusCode,
        headers: resp.headers
      });
});
```

shell/browser/api/electron_api_url_loader.cc
const GURL& url,
    bool first_auth_attempt,
    net::AuthChallengeInfo auth_info,
    network::mojom::URLResponseHeadPtr head,
    mojo::PendingRemote<network::mojom::AuthChallengeResponder>
        auth_challenge_responder) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  mojo::Remote<network::mojom::AuthChallengeResponder> auth_responder(
      std::move(auth_challenge_responder));
  
  
  
  auth_responder.set_disconnect_handler(base::BindOnce(
      &SimpleURLLoaderWrapper::Cancel, weak_factory_.GetWeakPtr()));
  auto cb = base::BindOnce(
      [](mojo::Remote<network::mojom::AuthChallengeResponder> auth_responder,
         gin::Arguments* args) {
        base::string16 username_str, password_str;
        if (!args->GetNext(&username_str) || !args->GetNext(&password_str)) {
          auth_responder->OnAuthCredentials(base::nullopt);
          return;
        }
        auth_responder->OnAuthCredentials(
            net::AuthCredentials(username_str, password_str));
      },
      std::move(auth_responder));
  Emit("login", auth_info, base::AdaptCallbackForRepeating(std::move(cb)));
}
void SimpleURLLoaderWrapper::Cancel() {