Writes the full history for a particular client.

def WriteClientSnapshotHistory(self, clients):
    """Writes the full history for a particular client."""
    if clients[0].client_id not in self.metadatas:
      raise db.UnknownClientError(clients[0].client_id)

    for client in clients:
      startup_info = client.startup_info
      client.startup_info = None

      snapshots = self.clients.setdefault(client.client_id, {})
      snapshots[client.timestamp] = client.SerializeToString()

      startup_infos = self.startup_history.setdefault(client.client_id, {})
      startup_infos[client.timestamp] = startup_info.SerializeToString()

      client.startup_info = startup_info