* Electron Version: 3.0.0-beta.1 or 3.0.0-beta.2
* Operating System (Platform and Version): macOS 10.13 (High Sierra)
* Last known working Electron version: 2.0.4

**Expected Behavior**
When a html5 notification is triggered from the renderer, a toast alert should appear

**Actual behavior**
No toast alert is appearing when a html5 notification is triggered from the renderer

**To Reproduce**
```sh
$ git clone https://github.com/VishwasShashidhar/electron-quick-start -b notifications-3beta
$ npm install
$ npm start || electron .
```
Click on the "send notification" button in the renderer.

**Screenshots**

***Working (2.0.4)***
![electron 2 0 4 notifications](https://user-images.githubusercontent.com/5968790/42554031-ea56866e-8500-11e8-91fe-36f87b4180f9.gif)

***Not Working (3.0.0-beta.2)***
![electron 3 0 0 beta 2 notifications](https://user-images.githubusercontent.com/5968790/42554088-22da29fa-8501-11e8-8ba6-22aa765c5eac.gif)

**Additional Information**
N/A
brightray/browser/platform_notification_service.cc
PlatformNotificationService::CheckPermissionOnIOThread(
    content::ResourceContext* resource_context,
    const GURL& origin,
    int render_process_id) {
  return blink::mojom::PermissionStatus::GRANTED;
}
void PlatformNotificationService::DisplayNotification(
    content::BrowserContext* browser_context,
    const std::string& notification_id,
    const GURL& origin,
    const content::PlatformNotificationData& notification_data,
    const content::NotificationResources& notification_resources) {
  auto* presenter = browser_client_->GetNotificationPresenter();
  if (!presenter)
    return;
  NotificationDelegateImpl* delegate =
      new NotificationDelegateImpl(notification_id);
  auto notification = presenter->CreateNotification(delegate, notification_id);
  if (notification) {
    browser_client_->WebNotificationAllowed(
        render_process_id_, base::Bind(&OnWebNotificationAllowed, notification,
                                       notification_resources.notification_icon,
                                       notification_data));
  }
}
void PlatformNotificationService::DisplayPersistentNotification(