@Override
        public void cancelNotification(Bundle bundle) {
            checkCaller();

            CancelNotificationArgs args = CancelNotificationArgs.fromBundle(bundle);

            TrustedWebActivityService.this.cancelNotification(args.platformTag, args.platformId);
        }
Used as a return value of {@link #getSmallIconId} when the icon is not provided.
customtabs/src/android/support/customtabs/trusted/TrustedWebActivityService.java