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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
if (success) {
    Emit("complete");
  } else {
    Emit("error", net::ErrorToString(loader_->NetError()));
  }
  loader_.reset();
  pinned_wrapper_.Reset();
  pinned_chunk_pipe_getter_.Reset();
}
void SimpleURLLoaderWrapper::OnRetry(base::OnceClosure start_retry) {}
void SimpleURLLoaderWrapper::OnResponseStarted(
    const GURL& final_url,
    const network::mojom::URLResponseHead& response_head) {
  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  v8::HandleScope scope(isolate);
  gin::Dictionary dict = gin::Dictionary::CreateEmpty(isolate);
  dict.Set("statusCode", response_head.headers->response_code());
  dict.Set("statusMessage", response_head.headers->GetStatusText());
  dict.Set("httpVersion", response_head.headers->GetHttpVersion());
  
  
  DCHECK(response_head.raw_request_response_info);
  dict.Set("rawHeaders",
           response_head.raw_request_response_info->response_headers);
  Emit("response-started", final_url, dict);
}
void SimpleURLLoaderWrapper::OnRedirect(