Add Finch experiment option to turn on/off QUIC 0-RTT in TLS versions.

Change-Id: I96e42510e0282b52a5aa5abc8529bd38807e3549
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2248478Reviewed-by: Nick Harper <nharper@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Renjie Tang <renjietang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779591}

components/network_session_configurator/browser/network_session_configurator.cc

@@ -346,6 +346,11 @@ bool ShouldQuicMigrateIdleSessions(
       GetVariationParam(quic_trial_params, "migrate_idle_sessions"), "true");
 }
 
+bool ShouldQuicDisableTlsZeroRtt(const VariationParameters& quic_trial_params) {
+  return base::LowerCaseEqualsASCII(
+      GetVariationParam(quic_trial_params, "disable_tls_zero_rtt"), "true");
+}
+
 int GetQuicRetransmittableOnWireTimeoutMilliseconds(
     const VariationParameters& quic_trial_params) {
   int value;
@@ -528,6 +533,10 @@ void ConfigureQuicParams(base::StringPiece quic_trial_group,
           base::TimeDelta::FromMilliseconds(
               initial_rtt_for_handshake_milliseconds);
     }
+
+    quic_params->disable_tls_zero_rtt =
+        ShouldQuicDisableTlsZeroRtt(quic_trial_params);
+
     int retransmittable_on_wire_timeout_milliseconds =
         GetQuicRetransmittableOnWireTimeoutMilliseconds(quic_trial_params);
     if (retransmittable_on_wire_timeout_milliseconds > 0) {

components/network_session_configurator/browser/network_session_configurator_unittest.cc

@@ -94,6 +94,7 @@ TEST_F(NetworkSessionConfiguratorTest, Defaults) {
   EXPECT_FALSE(quic_params_.allow_server_migration);
   EXPECT_TRUE(params_.quic_host_allowlist.empty());
   EXPECT_TRUE(quic_params_.retransmittable_on_wire_timeout.is_zero());
+  EXPECT_FALSE(quic_params_.disable_tls_zero_rtt);
 
   EXPECT_EQ(net::DefaultSupportedQuicVersions(),
             quic_params_.supported_versions);
@@ -443,6 +444,18 @@ TEST_F(NetworkSessionConfiguratorTest,
   EXPECT_TRUE(quic_params_.allow_port_migration);
 }
 
+TEST_F(NetworkSessionConfiguratorTest,
+       QuicDisableTlsZeroRttFromFieldTrialParams) {
+  std::map<std::string, std::string> field_trial_params;
+  field_trial_params["disable_tls_zero_rtt"] = "true";
+  variations::AssociateVariationParams("QUIC", "Enabled", field_trial_params);
+  base::FieldTrialList::CreateFieldTrial("QUIC", "Enabled");
+
+  ParseFieldTrials();
+
+  EXPECT_TRUE(quic_params_.disable_tls_zero_rtt);
+}
+
 TEST_F(NetworkSessionConfiguratorTest, PacketLengthFromFieldTrialParams) {
   std::map<std::string, std::string> field_trial_params;
   field_trial_params["max_packet_length"] = "1450";

net/quic/quic_context.h

@@ -165,6 +165,8 @@ struct NET_EXPORT QuicParams {
   // The initial rtt that will be used in crypto handshake if no cached
   // smoothed rtt is present.
   base::TimeDelta initial_rtt_for_handshake;
+  // If true, QUIC with TLS will not try 0-RTT connection.
+  bool disable_tls_zero_rtt = false;
 };
 
 // QuicContext contains QUIC-related variables that are shared across all of the

net/quic/quic_stream_factory.cc

@@ -1097,6 +1097,8 @@ QuicStreamFactory::QuicStreamFactory(
               features::kPartitionHttpServerPropertiesByNetworkIsolationKey)) {
   DCHECK(transport_security_state_);
   DCHECK(http_server_properties_);
+  if (params_.disable_tls_zero_rtt)
+    SetQuicReloadableFlag(quic_enable_zero_rtt_for_tls, false);
   InitializeMigrationOptions();
 }