- Electron version:
  We are using node 5.10.0, Chrome 49.0.2623.75, and Electron 1.0.1. 
- Operating system:
  Mac OS X 10.11.3 (15D21)

Trying to use the [Web Bluetooth APIs](https://developers.google.com/web/updates/2015/07/interact-with-ble-devices-on-the-web?hl=en#scan-for-bluetooth-devices) but when I run the Web Bluetooth demo code, the callbacks fail with the error:

`Argh! NotFoundError: User cancelled the requestDevice() chooser.`

main.js code:

```
// Module to control application life.
const {app} = electron;

// @link https://github.com/electron/electron/blob/master/docs/api/chrome-command-line-switches.md
app.commandLine.appendSwitch('enable-web-bluetooth', true);
```

Index.html code:

```
<a href="#" onclick="run();" class="scanDevices">Scan</a>
    <script>
    function run() {
        var filters = [{
    services: [0x1800, 0x1801, 0x1812]
  }];
          console.log('Requesting Bluetooth Device...');
  navigator.bluetooth.requestDevice({filters: filters})
  .then(device => {
    console.log('> Name:             ' + device.name);
    console.log('> Id:               ' + device.id);
    console.log('> UUIDs:            ' + device.uuids.join('\n' + ' '.repeat(20)));
    console.log('> Connected:        ' + device.gatt.connected);
  })
  .catch(error => {
    console.log('Argh! ' + error);
  });
  }
    </script>
```

Reference:
https://github.com/electron/electron/blob/master/atom/browser/atom_permission_manager.cc#L93

atom/browser/api/atom_api_web_contents.cc
blink::WebReferrerPolicyDefault);
  std::string user_agent;
  if (options.Get("userAgent", &user_agent))
    SetUserAgent(user_agent);
  std::string extra_headers;
  if (options.Get("extraHeaders", &extra_headers))
    params.extra_headers = extra_headers;
  params.transition_type = ui::PAGE_TRANSITION_TYPED;
  params.should_clear_history_list = true;
  params.override_user_agent = content::NavigationController::UA_OVERRIDE_TRUE;
  web_contents()->GetController().LoadURLWithParams(params);
  
  
  
  const auto view = web_contents()->GetRenderWidgetHostView();
  WebContentsPreferences* web_preferences =
      WebContentsPreferences::FromWebContents(web_contents());
  std::string color_name;
  if (web_preferences->web_preferences()->GetString(options::kBackgroundColor,
                                                    &color_name)) {
    view->SetBackgroundColor(ParseHexColor(color_name));
  } else {
    view->SetBackgroundColor(SK_ColorTRANSPARENT);
  }
  
  const auto host = static_cast<content::RenderWidgetHostImpl*>(
      view->GetRenderWidgetHost());
  host->disable_hidden_ = !background_throttling_;
}
void WebContents::DownloadURL(const GURL& url) {