Docs:
https://github.com/electron/electron/blob/master/docs/api/session.md#sesclearstoragedataoptions-callback

I was running into a strange error when calling the `clearStorageData` method. It was saying it was unable to process the argument at index 1, which I was not passing. After some research I found that the callback is currently required, but in my case I did not care to provide one. To fix it, I supplied an empty function. Here is my code:

```
Electron.remote.getCurrentWebContents().session.clearStorageData(
    {
        storages: [
            'appcache',
            'cookies',
            'filesystem',
            'indexdb',
            'localstorage',
            'shadercache',
            'websql',
            'serviceworkers',
        ],
        quotas: [
            'temporary',
            'persistent',
            'syncable',
        ],
    },
    function() {} // <--- I shouldn't have to do this
);
```
- Electron version: 1.2.7
- Operating system: macOS

atom/browser/api/atom_api_session.cc
const scoped_refptr<net::URLRequestContextGetter>& context_getter,
    const std::string& domains) {
  auto request_context = context_getter->GetURLRequestContext();
  auto auth_handler = request_context->http_auth_handler_factory();
  if (auth_handler) {
    auto auth_preferences = const_cast<net::HttpAuthPreferences*>(
        auth_handler->http_auth_preferences());
    if (auth_preferences)
      auth_preferences->set_server_whitelist(domains);
  }
}
}  
Session::Session(v8::Isolate* isolate, AtomBrowserContext* browser_context)
    : devtools_network_emulation_client_id_(base::GenerateGUID()),
      browser_context_(browser_context) {
  
  content::BrowserContext::GetDownloadManager(browser_context)->
      AddObserver(this);
  Init(isolate);
  AttachAsUserData(browser_context);
}
Session::~Session() {