backups: take a pattern instead of interval secs

part of #699

src/cron.js

@@ -4,8 +4,6 @@
 // If the patterns overlap all the time, then the task may not ever get a chance to run!
 // If you change this change dashboard patterns in settings.html
 const DEFAULT_CLEANUP_BACKUPS_PATTERN = '00 30 1,3,5,23 * * *',
-    DEFAULT_BOX_ENSURE_BACKUP_PATTERN_LT_6HOURS = '00 45 1,7,13,19 * * *',
-    DEFAULT_BOX_ENSURE_BACKUP_PATTERN_GT_6HOURS =  '00 45 1,3,5,23 * * *',
     DEFAULT_BOX_AUTOUPDATE_PATTERN = '00 00 1,3,5,23 * * *',
     DEFAULT_APP_AUTOUPDATE_PATTERN = '00 15 1,3,5,23 * * *';
 
@@ -179,16 +177,10 @@ function backupConfigChanged(value, tz) {
     debug(`backupConfigChanged: interval ${value.intervalSecs} (${tz})`);
 
     if (gJobs.backup) gJobs.backup.stop();
-    let pattern;
-    if (value.intervalSecs <= 6 * 60 * 60) {
-        pattern = DEFAULT_BOX_ENSURE_BACKUP_PATTERN_LT_6HOURS; // no option but to backup in the middle of the day
-    } else {
-        pattern = DEFAULT_BOX_ENSURE_BACKUP_PATTERN_GT_6HOURS; // avoid middle of the day backups. it's 45 to not overlap auto-updates
-    }
 
     gJobs.backup = new CronJob({
-        cronTime: pattern,
-        onTick: backups.ensureBackup.bind(null, auditSource.CRON, NOOP_CALLBACK),
+        cronTime: value.schedulePattern,
+        onTick: backups.startBackupTask.bind(null, auditSource.CRON, NOOP_CALLBACK),
         start: true,
         timeZone: tz
     });