Remove unused fields in contractor (#1486)

autopilot/contractor/contractor.go

@@ -132,9 +132,6 @@ type (
 		revisionSubmissionBuffer  uint64
 
 		firstRefreshFailure map[types.FileContractID]time.Time
-
-		shutdownCtx       context.Context
-		shutdownCtxCancel context.CancelFunc
 	}
 
 	scoredHost struct {
@@ -167,7 +164,6 @@ type (
 
 func New(bus Bus, alerter alerts.Alerter, logger *zap.SugaredLogger, revisionSubmissionBuffer uint64, revisionBroadcastInterval time.Duration) *Contractor {
 	logger = logger.Named("contractor")
-	ctx, cancel := context.WithCancel(context.Background())
 	return &Contractor{
 		bus:     bus,
 		alerter: alerter,
@@ -179,17 +175,9 @@ func New(bus Bus, alerter alerts.Alerter, logger *zap.SugaredLogger, revisionSub
 		revisionSubmissionBuffer:  revisionSubmissionBuffer,
 
 		firstRefreshFailure: make(map[types.FileContractID]time.Time),
-
-		shutdownCtx:       ctx,
-		shutdownCtxCancel: cancel,
 	}
 }
 
-func (c *Contractor) Close() error {
-	c.shutdownCtxCancel()
-	return nil
-}
-
 func (c *Contractor) PerformContractMaintenance(ctx context.Context, w Worker, state *MaintenanceState) (bool, error) {
 	return performContractMaintenance(newMaintenanceCtx(ctx, state), c.alerter, c.bus, c.churn, w, c, c, c, c.logger)
 }