ClientOption is a broker Option which allows google pubsub client options to be set for the client.

MaxExtension is the maximum period for which the Subscription should automatically extend the ack deadline for each message.

MaxOutstandingMessages sets the maximum number of unprocessed messages (unacknowledged but not yet expired) to receive.

NewBroker creates a new google pubsub broker.

ProjectID provides an option which sets the google project id.