“SHATTERED GLASS” is a slim, reedy film. It presents the now-familiar story of Stephen Glass as a cautionary tale and then offers up a hero in the person of Chuck Lane, the New Republic editor who fired Glass. As a journalism movie, “Shattered Glass” is middle-rank, not up to the standards of “The Insider” or “Live from Baghdad,” but better than, say, “I Love Trouble.” It is too parochial to find a broad audience and too slight to win any major awards. And yet, it is an important movie to discuss because it attempts to pull an ugly trick: While “Shattered Glass” presents itself as an exposé of journalism’s sins, it is actually a carefully prepared whitewash.