code: public void triggerRegisteredSessionStepObserver(int observerId, long timeUsedInMillis) {
      UsageSessionObserver observer = usageSessionObserversById.get(observerId);
      long sessionStepTimeInMillis = observer.sessionStepDuration.toMillis();
      Intent intent =
          new Intent()
              .putExtra(UsageStatsManager.EXTRA_OBSERVER_ID, observerId)
              .putExtra(UsageStatsManager.EXTRA_TIME_LIMIT, sessionStepTimeInMillis)
              .putExtra(UsageStatsManager.EXTRA_TIME_USED, timeUsedInMillis);
      try {
        observer.sessionStepTriggeredIntent.send(RuntimeEnvironment.application, 0, intent);
      } catch (CanceledException e) {
        throw new RuntimeException(e);
      }
    }
docs: Triggers a currently registered {@link UsageSessionObserver} with {@code observerId}.
  
  <p>The observer SHOULD be registered afterwards.