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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
BACKGROUND_PAGE,  
    BROWSER_WINDOW,  
    REMOTE,  
    WEB_VIEW,  
    OFF_SCREEN,  
  };
  
  using PrintToPDFCallback =
      base::Callback<void(v8::Local<v8::Value>, v8::Local<v8::Value>)>;
  
  static mate::Handle<WebContents> CreateFrom(
      v8::Isolate* isolate, content::WebContents* web_contents);
  static mate::Handle<WebContents> CreateFrom(
      v8::Isolate* isolate, content::WebContents* web_contents, Type type);
  
  static mate::Handle<WebContents> Create(
      v8::Isolate* isolate, const mate::Dictionary& options);
  static void BuildPrototype(v8::Isolate* isolate,
                             v8::Local<v8::FunctionTemplate> prototype);
  int64_t GetID() const;
  int GetProcessID() const;
  Type GetType() const;
  bool Equal(const WebContents* web_contents) const;
  void LoadURL(const GURL& url, const mate::Dictionary& options);
  void DownloadURL(const GURL& url);
  GURL GetURL() const;
  base::string16 GetTitle() const;