Revert change to use report timestamp

This reverts commit 6b72246fe6.

The app merges reports within a 15-second window of its own time, so
if one or more probes have a time that is several seconds different
they will get excluded from the window.

app/collector.go

@@ -348,7 +348,6 @@ func replay(a Adder, timestamps []time.Time, reports []report.Report) {
 	due := time.Now()
 	for {
 		for i, r := range reports {
-			r.TS = due
 			a.Add(nil, r, nil)
 			due = due.Add(delays[i])
 			delay := due.Sub(time.Now())

app/multitenant/aws_collector.go

@@ -538,7 +538,7 @@ func (c *awsCollector) Add(ctx context.Context, rep report.Report, buf []byte) e
 	}
 
 	// first, put the report on s3
-	rowKey, colKey := calculateDynamoKeys(userid, rep.TS)
+	rowKey, colKey := calculateDynamoKeys(userid, time.Now())
 	reportKey, err := calculateReportKey(rowKey, colKey)
 	if err != nil {
 		return err

app/multitenant/billing_emitter.go

@@ -59,7 +59,7 @@ func (e *BillingEmitter) Add(ctx context.Context, rep report.Report, buf []byte)
 		// proceeding.
 		return err
 	}
-	rowKey, colKey := calculateDynamoKeys(userID, rep.TS)
+	rowKey, colKey := calculateDynamoKeys(userID, now)
 
 	interval := e.reportInterval(rep)
 	// Cache the last-known value of interval for this user, and use

app/router.go

@@ -148,10 +148,6 @@ func RegisterReportPostHandler(a Adder, router *mux.Router) {
 			buf, _ = rpt.WriteBinary()
 		}
 
-		// If it didn't come in with a timestamp, give it one now
-		if rpt.TS.IsZero() {
-			rpt.TS = time.Now().UTC()
-		}
 		if err := a.Add(ctx, *rpt, buf.Bytes()); err != nil {
 			log.Errorf("Error Adding report: %v", err)
 			respondWith(w, http.StatusInternalServerError, err)