Metric & meta-metric for CECPQ1 handshake latency.

net/socket/ssl_client_socket.cc

Index: net/socket/ssl_client_socket.cc
diff --git a/net/socket/ssl_client_socket.cc b/net/socket/ssl_client_socket.cc
index 3c3858e3ae3b6cf299255df600473fd01dc9fc0d..93be1d31a8317f76f3be271c35035b43cad393c8 100644
--- a/net/socket/ssl_client_socket.cc
+++ b/net/socket/ssl_client_socket.cc
@@ -4,9 +4,11 @@
 
 #include "net/socket/ssl_client_socket.h"
 
+#include "base/feature_list.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_util.h"
+#include "build/build_config.h"
 #include "crypto/ec_private_key.h"
 #include "net/base/net_errors.h"
 #include "net/socket/ssl_client_socket_impl.h"
@@ -15,6 +17,14 @@
 
 namespace net {
 
+namespace {
+#if !defined(OS_NACL)
+const base::Feature kPostQuantumExperiment{"SSLPostQuantumExperiment",

[jwd, 2016/08/01 15:53:53]

We tend not to like features including "experiment" in the name. 

Mostly an FYI, since you already have this deployed, and it would be a hassle to
change.

[mab, 2016/08/09 21:04:41]

OK, leaving alone.  Would you have called it "SSLPostQuantum"?

"Experiment" aims to convey that this will never be enabled for all users, &
that we plan to turn it off in a couple years regardless of outcome.

[jwd, 2016/08/10 17:39:26]

Probably SSLPostQuantum, but I might have gone with SSLPostQuantumExperiment
too, for the reason you describe. Though I think SSLPostQuantum, and a comment
describing the temporaryness of it would be better.

So actually, can you add a comment that this isn't a permanent thing, and should
be removed in the future? ;)

+                                           base::FEATURE_DISABLED_BY_DEFAULT};
+#endif
+
+}  // namespace
+
 SSLClientSocket::SSLClientSocket()
     : signed_cert_timestamps_received_(false),
       stapled_ocsp_response_received_(false),
@@ -98,6 +108,14 @@ bool SSLClientSocket::IgnoreCertError(int error, int load_flags) {
          IsCertificateError(error);
 }
 
+// static
+bool SSLClientSocket::IsPostQuantumExperimentEnabled() {
+#if !defined(OS_NACL)
+  return base::FeatureList::IsEnabled(kPostQuantumExperiment);
+#endif
+  return false;
+}
+
 void SSLClientSocket::RecordNegotiationExtension() {
   if (negotiation_extension_ == kExtensionUnknown)
     return;