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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/common_web_contents_delegate.cc
int request_id,
    const std::string& file_system_path) {
  devtools_indexing_jobs_.erase(request_id);
  base::FundamentalValue request_id_value(request_id);
  base::StringValue file_system_path_value(file_system_path);
  web_contents_->CallClientFunction("DevToolsAPI.indexingDone",
                                    &request_id_value,
                                    &file_system_path_value,
                                    nullptr);
}
void CommonWebContentsDelegate::OnDevToolsSearchCompleted(
    int request_id,
    const std::string& file_system_path,
    const std::vector<std::string>& file_paths) {
  base::ListValue file_paths_value;
  for (const auto& file_path : file_paths) {
    file_paths_value.AppendString(file_path);
  }
  base::FundamentalValue request_id_value(request_id);
  base::StringValue file_system_path_value(file_system_path);
  web_contents_->CallClientFunction("DevToolsAPI.searchCompleted",
                                    &request_id_value,
                                    &file_system_path_value,
                                    &file_paths_value);
}
void CommonWebContentsDelegate::SetHtmlApiFullscreen(bool enter_fullscreen) {