net/http/httptrace: add clarification never added to CL 67430

Updates #19761

Change-Id: Iac3bd4c40002f8e348452b50bff54dee3210d447
Reviewed-on: https://go-review.googlesource.com/121236
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/net/http/httptrace/trace.go b/src/net/http/httptrace/trace.go
index 17878898815c5c8c5a352f120e4238a80e7cfb75..3a627412b3430660f0537f7d949e18b37d5e884b 100644 (file)
--- a/src/net/http/httptrace/trace.go
+++ b/src/net/http/httptrace/trace.go
@@ -143,7 +143,8 @@ type ClientTrace struct {
        TLSHandshakeDone func(tls.ConnectionState, error)
 
        // WroteHeaderField is called after the Transport has written
-       // each request header.
+       // each request header. At the time of this call the values
+       // might be buffered and not yet written to the network.
        WroteHeaderField func(key string, value []string)
 
        // WroteHeaders is called after the Transport has written