private static extern XSAPI_RESULT XboxLiveUserSignInSilently( IntPtr xboxLiveUserPtr, XSAPI_SIGN_IN_COMPLETION_ROUTINE completionRoutine, IntPtr completionRoutineContext, Int64 taskGroupId);
private static extern XSAPI_RESULT XboxLiveUserSignInWithCoreDispatcher( IntPtr xboxLiveUserPtr, IntPtr coreDispatcher, XSAPI_SIGN_IN_COMPLETION_ROUTINE completionRoutine, IntPtr completionRoutineContext, Int64 taskGroupId);