Updates flow objects in the database.

    Args:
      client_id: The client id on which this flow is running.
      flow_id: The id of the flow to update.
      flow_obj: An updated rdf_flow_objects.Flow object.
      flow_state: An update rdf_flow_objects.Flow.FlowState value.
      client_crash_info: A rdf_client.ClientCrash object to store with the flow.
      pending_termination: An rdf_flow_objects.PendingFlowTermination object.
        Indicates that this flow is scheduled for termination.
      processing_on: Worker this flow is currently processed on.
      processing_since: Timstamp when the worker started processing this flow.
      processing_deadline: Time after which this flow will be considered stuck
        if processing hasn't finished.

def UpdateFlow(self,
                 client_id,
                 flow_id,
                 flow_obj=unchanged,
                 flow_state=unchanged,
                 client_crash_info=unchanged,
                 pending_termination=unchanged,
                 processing_on=unchanged,
                 processing_since=unchanged,
                 processing_deadline=unchanged):
    """Updates flow objects in the database.

    Args:
      client_id: The client id on which this flow is running.
      flow_id: The id of the flow to update.
      flow_obj: An updated rdf_flow_objects.Flow object.
      flow_state: An update rdf_flow_objects.Flow.FlowState value.
      client_crash_info: A rdf_client.ClientCrash object to store with the flow.
      pending_termination: An rdf_flow_objects.PendingFlowTermination object.
        Indicates that this flow is scheduled for termination.
      processing_on: Worker this flow is currently processed on.
      processing_since: Timstamp when the worker started processing this flow.
      processing_deadline: Time after which this flow will be considered stuck
        if processing hasn't finished.
    """