Synchronous accessor for the current authResponse. The synchronous nature of this method is what sets it apart from the other login methods.
This method is similar in nature to FB.getLoginStatus(), but it returns just the authResponse object. Many parts of your application already assume the user is connected with your application. In such cases, you may want to avoid the overhead of making asynchronous calls.
NOTE: You should never use this method at page load time. Generally, it is safer to use FB.getLoginStatus() if you are unsure.
For documentation on the AuthResponse object itself, please see FB.getLoginStatus()