Reads the full startup history for a particular client.

def ReadClientStartupInfoHistory(self, client_id, timerange=None):
    """Reads the full startup history for a particular client."""
    from_time, to_time = self._ParseTimeRange(timerange)

    history = self.startup_history.get(client_id)
    if not history:
      return []
    res = []
    for ts in sorted(history, reverse=True):
      if ts < from_time or ts > to_time:
        continue

      client_data = rdf_client.StartupInfo.FromSerializedString(history[ts])
      client_data.timestamp = ts
      res.append(client_data)
    return res