### Issue Details

* **Electron Version:**
  * 7.0.0-beta.5
* **Operating System:**
  * Windows
* **Last Known Working Electron version:**
  * 6

### Expected Behavior
```js
const filter = {
  domain: 'facebook.com'
}
const cookies = await webContents.session.cookies.get(filter) // will resolve with actual cookies
```

### Actual Behavior
```js
const filter = {
  domain: 'facebook.com',
  // url: 'https://facebook.com' - NOTE: filtering by url is working
}
const cookies = await webContents.session.cookies.get(filter) // is returning empty array
```

### To Reproduce
```js
const filter = {
  domain: 'facebook.com'
}
const cookies = await webContents.session.cookies.get(filter)
```

Filter by `domain` is returning empty array, but if I try to filter using `url` is returning the actual cookies.

Tested on all `7` beta versions.
On `6` filtering by domain was worked.

shell/browser/api/atom_api_cookies.cc
util::Promise<void*> promise(isolate());
  v8::Local<v8::Promise> handle = promise.GetHandle();
  auto* storage_partition = content::BrowserContext::GetDefaultStoragePartition(
      browser_context_.get());
  auto* manager = storage_partition->GetCookieManagerForBrowserProcess();
  manager->FlushCookieStore(base::BindOnce(
      util::Promise<void*>::ResolveEmptyPromise, std::move(promise)));
  return handle;
}
void Cookies::OnCookieChanged(const CookieDetails* details) {
  Emit("changed", gin::ConvertToV8(isolate(), *(details->cookie)),
       gin::ConvertToV8(isolate(), details->cause),
       gin::ConvertToV8(isolate(), details->removed));
}
gin::Handle<Cookies> Cookies::Create(v8::Isolate* isolate,
                                     AtomBrowserContext* browser_context) {
  return gin::CreateHandle(isolate, new Cookies(isolate, browser_context));
}
void Cookies::BuildPrototype(v8::Isolate* isolate,
                             v8::Local<v8::FunctionTemplate> prototype) {
  prototype->SetClassName(gin::StringToV8(isolate, "Cookies"));
  mate::ObjectTemplateBuilder(isolate, prototype->PrototypeTemplate())
      .SetMethod("get", &Cookies::Get)
      .SetMethod("remove", &Cookies::Remove)
      .SetMethod("set", &Cookies::Set)
      .SetMethod("flushStore", &Cookies::FlushStore);
}
}  
}