LogDog: Implement prefix registration in Butler.

client/internal/logdog/butler/bundler/bundler.go

Index: client/internal/logdog/butler/bundler/bundler.go
diff --git a/client/internal/logdog/butler/bundler/bundler.go b/client/internal/logdog/butler/bundler/bundler.go
index 94a6234046a628a0ce2654d1b516c0130e8b2ede..b8a19ea439737a7514937aebd5d1769c3cc52498 100644
--- a/client/internal/logdog/butler/bundler/bundler.go
+++ b/client/internal/logdog/butler/bundler/bundler.go
@@ -30,8 +30,6 @@ type Config struct {
 	Project config.ProjectName
 	// Prefix is the common prefix for this set of streams.
 	Prefix types.StreamName
-	// Secret is the prefix secret for this set of streams.
-	Secret []byte
 
 	// MaxBufferedBytes is the maximum number of bytes to buffer in memory per
 	// stream.
@@ -192,7 +190,6 @@ func (b *Bundler) makeBundles() {
 				Timestamp: google.NewTimestamp(b.getClock().Now()),
 				Project:   string(b.c.Project),
 				Prefix:    string(b.c.Prefix),
-				Secret:    b.c.Secret,
 			},
 		}
 		var oldestContentTime time.Time