Add a returns clause to the matchesInterruptionFilter javadoc.

Bug: 17641219
Change-Id: I4f1949902bf872823389f3db8e694e370e113295

core/java/android/service/notification/NotificationListenerService.java

@@ -760,6 +760,9 @@ public abstract class NotificationListenerService extends Service {
         /**
          * Returns whether the notification matches the user's interruption
          * filter.
+         *
+         * @return {@code true} if the notification is allowed by the filter, or
+         * {@code false} if it is blocked.
          */
         public boolean matchesInterruptionFilter() {
             return mMatchesInterruptionFilter;