- Electron version: 1.2.2
- Operating system: Linux

This is a problem only in linux. It works in OSX.

``` javascript
win.hide()
win.capturePage(function(img){
 // never called
})
```

shell/browser/api/electron_api_web_contents.cc
base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
                                                base::BlockingType::WILL_BLOCK);
  DCHECK(!path.empty());
  base::AppendToFile(path, content.data(), content.size());
}
PrefService* GetPrefService(content::WebContents* ontents) {
  auto* context = ontents->GetBrowserContext();
  return static_cast<electron::ElectronBrowserContext*>(context)->prefs();
}
std::map<std::string, std::string> GetAddedFileSystemPaths(
    content::WebContents* ontents) {
  auto* pref_service = GetPrefService(ontents);
  const base::DictionaryValue* file_system_paths_value =
      pref_service->GetDictionary(prefs::kDevToolsFileSystemPaths);
  std::map<std::string, std::string> result;
  if (file_system_paths_value) {
    base::DictionaryValue::Iterator it(*file_system_paths_value);
    for (; !it.IsAtEnd(); it.Advance()) {
      std::string type =
          it.value().is_string() ? it.value().GetString() : std::string();
      result[it.key()] = type;
    }
  }
  return result;
}
bool IsDevToolsFileSystemAdded(content::WebContents* ontents,