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* Electron version: 1.6.1
* Operating system: macOS

### Expected behavior

navigator.geolocation.getCurrentPosition runs in background

### Actual behavior

the entire UI is frozen

### How to reproduce

```js
    navigator.geolocation.getCurrentPosition((pos) => {
      console.log('POS: ' + pos);
    }, (err) => {
      console.log('Geolocation error: ', err);
    }, {enableHighAccuracy: false});
```
atom/browser/api/atom_api_web_contents.h
#ifndef ATOM_BROWSER_API_ATOM_API_WEB_CONTENTS_H_
#define ATOM_BROWSER_API_ATOM_API_WEB_CONTENTS_H_
#include <string>
#include <vector>
#include "atom/browser/api/frame_subscriber.h"
#include "atom/browser/api/save_page_handler.h"
#include "atom/browser/api/trackable_object.h"
#include "atom/browser/common_web_contents_delegate.h"
#include "content/common/cursors/webcursor.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/common/favicon_url.h"
#include "native_mate/handle.h"
#include "ui/gfx/image/image.h"
namespace blink {
struct WebDeviceEmulationParams;
}
namespace brightray {
class InspectableWebContents;