* Electron version: 1.6.2
* Operating system: macOS 10.12

### Expected behavior

Requests sent with the net module should behave one of two ways regarding cookies.
- Either not care about cookies at all, and neither store them nor send them back automatically.
- Or, fully handle cookies, store them when getting a `set-cookie` header, and send them back when necessary, automatically (with the possibility of an option to disable this behaviour)

### Actual behavior

Requests sent with the net module store cookies in the Session used by the request when getting a `set-cookie` header, but do not send them back afterwards.

### How to reproduce

```bash
git clone https://github.com/arantes555/electron-net-cookies-testcase.git && cd electron-net-cookies-testcase
npm i
npm start
```
output: 
```
Server started
REQUEST-HEADERS { 'Accept-Encoding': 'gzip, deflate',
  'Accept-Language': 'fr',
  'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Electron/1.6.2 Safari/537.36' }
Response SET-COOKIE: undefined
STORED COOKIES: []
REQUEST-HEADERS { 'Accept-Encoding': 'gzip, deflate',
  'Accept-Language': 'fr',
  'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Electron/1.6.2 Safari/537.36' }
Response SET-COOKIE: a=1,b=1
STORED COOKIES: [{"name":"a","value":"1","domain":"localhost"},{"name":"b","value":"1","domain":"localhost"}]
REQUEST-HEADERS { 'Accept-Encoding': 'gzip, deflate',
  'Accept-Language': 'fr',
  'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Electron/1.6.2 Safari/537.36' }
Response SET-COOKIE: a=1,b=1
```

Btw, if I'm reporting multiple issues with the net module these days, it's because I'm working on https://github.com/arantes555/electron-fetch , if you wanna take a look :)
shell/browser/api/electron_api_url_loader.cc
v8::Isolate* isolate,
      v8::Local<v8::Function> body_func,
      mojo::PendingReceiver<network::mojom::ChunkedDataPipeGetter>
          chunked_data_pipe_getter) {
    return gin::CreateHandle(
        isolate, new JSChunkedDataPipeGetter(
                     isolate, body_func, std::move(chunked_data_pipe_getter)));
  }
  
  gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
      v8::Isolate* isolate) override {
    return gin::Wrappable<JSChunkedDataPipeGetter>::GetObjectTemplateBuilder(
               isolate)
        .SetMethod("write", &JSChunkedDataPipeGetter::WriteChunk)
        .SetMethod("done", &JSChunkedDataPipeGetter::Done);
  }
  static gin::WrapperInfo kWrapperInfo;
  ~JSChunkedDataPipeGetter() override = default;
 private:
  JSChunkedDataPipeGetter(
      v8::Isolate* isolate,
      v8::Local<v8::Function> body_func,
      mojo::PendingReceiver<network::mojom::ChunkedDataPipeGetter>
          chunked_data_pipe_getter)
      : isolate_(isolate), body_func_(isolate, body_func) {
    receiver_.Bind(std::move(chunked_data_pipe_getter));
  }
  
  void GetSize(GetSizeCallback callback) override {