Change CryptoHandshakeMessage::GetTaglist to tag a QuicTagVector*

net/quic/core/quic_config.cc

Index: net/quic/core/quic_config.cc
diff --git a/net/quic/core/quic_config.cc b/net/quic/core/quic_config.cc
index 745370895e49ef172d91cddc84b1d0435c058306..b7af205e715620dfeded49022788b011e1fcf266 100644
--- a/net/quic/core/quic_config.cc
+++ b/net/quic/core/quic_config.cc
@@ -232,10 +232,7 @@ QuicErrorCode QuicFixedTagVector::ProcessPeerHello(
     HelloType hello_type,
     string* error_details) {
   DCHECK(error_details != nullptr);
-  const QuicTag* received_tags;
-  size_t received_tags_length;
-  QuicErrorCode error =
-      peer_hello.GetTaglist(tag_, &received_tags, &received_tags_length);

[Nico, 2017/05/27 00:34:32]

Here, if this failed the 2nd time, the LHS would keep the tags from the first
time around
 Now it clears them all. Ok?

[Ryan Hamilton, 2017/05/27 00:39:54]

Interesting point! Not a problem given how this is used, thankfully.

[Ryan Hamilton, 2017/05/28 01:29:19]

Interestingly, even though we don't make use of the behavior you described, we
do have a unit test of it, so I changed this to use the old behavior. Thanks for
spotting this! 

+  QuicErrorCode error = peer_hello.GetTaglist(tag_, &receive_values_);
   switch (error) {
     case QUIC_CRYPTO_MESSAGE_PARAMETER_NOT_FOUND:
       if (presence_ == PRESENCE_OPTIONAL) {
@@ -246,9 +243,6 @@ QuicErrorCode QuicFixedTagVector::ProcessPeerHello(
     case QUIC_NO_ERROR:
       QUIC_DVLOG(1) << "Received Connection Option tags from receiver.";
       has_receive_values_ = true;
-      for (size_t i = 0; i < received_tags_length; ++i) {
-        receive_values_.push_back(received_tags[i]);
-      }
       break;
     default:
       *error_details = "Bad " + QuicTagToString(tag_);