* 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
size_callback_ = std::move(callback);
  }
  void StartReading(mojo::ScopedDataPipeProducerHandle pipe) override {
    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
    if (body_func_.IsEmpty()) {
      LOG(ERROR) << "Tried to read twice from a JSChunkedDataPipeGetter";
      
      return;
    }
    data_producer_ = std::make_unique<mojo::DataPipeProducer>(std::move(pipe));
    v8::HandleScope handle_scope(isolate_);
    v8::MicrotasksScope script_scope(isolate_,
                                     v8::MicrotasksScope::kRunMicrotasks);
    auto maybe_wrapper = GetWrapper(isolate_);
    v8::Local<v8::Value> wrapper;
    if (!maybe_wrapper.ToLocal(&wrapper)) {
      return;
    }
    v8::Local<v8::Value> argv[] = {wrapper};
    node::Environment* env = node::Environment::GetCurrent(isolate_);
    auto global = env->context()->Global();
    node::MakeCallback(isolate_, global, body_func_.Get(isolate_),
                       node::arraysize(argv), argv, {0, 0});
  }
  v8::Local<v8::Promise> WriteChunk(v8::Local<v8::Value> buffer_val) {