title: OnRequestPermissionsResultCallback not triggering in PreferenceFragment
body: <pre><code>import android.preference.PreferenceFragment;
  import android.support.v13.app.FragmentCompat;
  import android.support.v4.app.ActivityCompat;
  import android.support.v4.content.ContextCompat;
  
  public class Preferences extends PreferenceFragment implements OnPreferenceClickListener, FragmentCompat.OnRequestPermissionsResultCallback {
  if (ContextCompat.checkSelfPermission(activity, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
     != PackageManager.PERMISSION_GRANTED) {
  ActivityCompat.requestPermissions(activity,
        new String[]{ android.Manifest.permission.WRITE_EXTERNAL_STORAGE },
        Constant.WRITE_STORAGE_PERMISSION);
  
  }
  
  public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grants) { }
  </code></pre>
  
  <p>I'm trying to get the new permissions. The dialog shows up requesting the permission when it should, but onRequestPermissionResult it's never called, be it rejection or acceptance.</p>
  
  <p>Any idea? The examples are all using Activity and not a Fragment, so that might be the problem. Also, I'm not sure which Compat I should be using (v4 vs v13). Min SDK is 14.</p>