Update TrackSelectionDialog.java

Fix a super tiny typo.

demos/main/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionDialog.java

@@ -306,7 +306,7 @@ public final class TrackSelectionDialog extends DialogFragment {
     }
     }
   }
   }
 
 
-  /** Fragment to show a track seleciton in tab of the track selection dialog. */
+  /** Fragment to show a track selection in tab of the track selection dialog. */
   public static final class TrackSelectionViewFragment extends Fragment
   public static final class TrackSelectionViewFragment extends Fragment
       implements TrackSelectionView.TrackSelectionListener {
       implements TrackSelectionView.TrackSelectionListener {