LogDog: Implement prefix registration in Butler.

client/cmd/logdog_butler/subcommand_stream.go

Index: client/cmd/logdog_butler/subcommand_stream.go
diff --git a/client/cmd/logdog_butler/subcommand_stream.go b/client/cmd/logdog_butler/subcommand_stream.go
index 17e8268eea093bca036001db1fd301cad323b578..2d1324c8e6de784b435601eafcf7014803800334 100644
--- a/client/cmd/logdog_butler/subcommand_stream.go
+++ b/client/cmd/logdog_butler/subcommand_stream.go
@@ -68,8 +68,16 @@ func (cmd *streamCommandRun) Run(app subcommands.Application, args []string) int
 		streamFile = file
 	}
 
+	// We think everything should work. Configure our Output instance.
+	output, err := a.configOutput()
+	if err != nil {
+		log.WithError(err).Errorf(a, "Failed to create output instance.")
+		return runtimeErrorReturnCode
+	}
+	defer output.Close()
+
 	// Instantiate our Processor.
-	err := a.Main(func(b *butler.Butler) error {
+	err = a.runWithButler(output, func(b *butler.Butler) error {
 		if err := b.AddStream(streamFile, cmd.stream.properties()); err != nil {
 			return err
 		}