Reads the full history for a particular client.

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

    history = self.clients.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_obj = rdf_objects.ClientSnapshot.FromSerializedString(history[ts])
      client_obj.timestamp = ts
      client_obj.startup_info = rdf_client.StartupInfo.FromSerializedString(
          self.startup_history[client_id][ts])
      res.append(client_obj)
    return res