const compress/gzip.BestCompression

4 uses

	compress/gzip (current package)
		gzip.go#L21: 	BestCompression    = flate.BestCompression
		gzip.go#L61: 	if level < HuffmanOnly || level > BestCompression {
		gzip.go#L162: 		if z.level == BestCompression {

	google.golang.org/grpc
		rpc_util.go#L73: 	if level < gzip.DefaultCompression || level > gzip.BestCompression {