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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.cc
return web_contents()->GetURL();
}
base::string16 WebContents::GetTitle() const {
  return web_contents()->GetTitle();
}
bool WebContents::IsLoading() const {
  return web_contents()->IsLoading();
}
bool WebContents::IsLoadingMainFrame() const {
  
  
  return (web_contents()->GetLastCommittedURL().is_empty() ||
          web_contents()->GetSiteInstance() !=
          web_contents()->GetPendingSiteInstance()) && IsLoading();
}
bool WebContents::IsWaitingForResponse() const {
  return web_contents()->IsWaitingForResponse();
}
void WebContents::Stop() {
  web_contents()->Stop();
}
void WebContents::GoBack() {
  atom::AtomBrowserClient::SuppressRendererProcessRestartForOnce();
  web_contents()->GetController().GoBack();
}
void WebContents::GoForward() {
  atom::AtomBrowserClient::SuppressRendererProcessRestartForOnce();
  web_contents()->GetController().GoForward();
}
void WebContents::GoToOffset(int offset) {