Add cronet experiment option to allow stale DNS racing experiment on cronet.

Bug: 787942
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;master.tryserver.chromium.android:android_cronet_tester
Change-Id: Ia9d210d3d427de332dae4f7ad7fb988239819926
Reviewed-on: https://chromium-review.googlesource.com/c/1289158
Commit-Queue: Renjie Tang <renjietang@chromium.org>
Reviewed-by: Misha Efimov <mef@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600901}

components/cronet/url_request_context_config.cc

@@ -76,6 +76,7 @@ const char kQuicUserAgentId[] = "user_agent_id";
 const char kQuicMigrateSessionsEarlyV2[] = "migrate_sessions_early_v2";
 const char kQuicRetryOnAlternateNetworkBeforeHandshake[] =
     "retry_on_alternate_network_before_handshake";
+const char kQuicRaceStaleDNSOnConnection[] = "race_stale_dns_on_connection";
 const char kQuicDisableBidirectionalStreams[] =
     "quic_disable_bidirectional_streams";
 const char kQuicRaceCertVerification[] = "race_cert_verification";
@@ -443,6 +444,13 @@ void URLRequestContextConfig::ParseAndSetExperimentalOptions(
             quic_retry_on_alternate_network_before_handshake;
       }
 
+      bool quic_race_stale_dns_on_connection = false;
+      if (quic_args->GetBoolean(kQuicRaceStaleDNSOnConnection,
+                                &quic_race_stale_dns_on_connection)) {
+        session_params->quic_race_stale_dns_on_connection =
+            quic_race_stale_dns_on_connection;
+      }
+
       bool quic_disable_bidirectional_streams = false;
       if (quic_args->GetBoolean(kQuicDisableBidirectionalStreams,
                                 &quic_disable_bidirectional_streams)) {

components/cronet/url_request_context_config_unittest.cc

@@ -204,6 +204,7 @@ TEST(URLRequestContextConfigTest, TestExperimentalOptionParsing) {
   EXPECT_FALSE(params->quic_migrate_sessions_on_network_change_v2);
   EXPECT_FALSE(params->quic_migrate_sessions_early_v2);
   EXPECT_FALSE(params->quic_retry_on_alternate_network_before_handshake);
+  EXPECT_FALSE(params->quic_race_stale_dns_on_connection);
 
   // Check race_cert_verification.
   EXPECT_TRUE(params->quic_race_cert_verification);
@@ -581,6 +582,57 @@ TEST(URLRequestContextConfigTest, SetQuicConnectionMigrationV2Options) {
       4, params->quic_max_migrations_to_non_default_network_on_path_degrading);
 }
 
+TEST(URLRequestContextConfigTest, SetQuicStaleDNSracing) {
+  base::test::ScopedTaskEnvironment scoped_task_environment_(
+      base::test::ScopedTaskEnvironment::MainThreadType::IO);
+
+  URLRequestContextConfig config(
+      // Enable QUIC.
+      true,
+      // QUIC User Agent ID.
+      "Default QUIC User Agent ID",
+      // Enable SPDY.
+      true,
+      // Enable Brotli.
+      false,
+      // Type of http cache.
+      URLRequestContextConfig::HttpCacheType::DISK,
+      // Max size of http cache in bytes.
+      1024000,
+      // Disable caching for HTTP responses. Other information may be stored in
+      // the cache.
+      false,
+      // Storage path for http cache and cookie storage.
+      "/data/data/org.chromium.net/app_cronet_test/test_storage",
+      // Accept-Language request header field.
+      "foreign-language",
+      // User-Agent request header field.
+      "fake agent",
+      // JSON encoded experimental options.
+      "{\"QUIC\":{\"race_stale_dns_on_connection\":true}}",
+      // MockCertVerifier to use for testing purposes.
+      std::unique_ptr<net::CertVerifier>(),
+      // Enable network quality estimator.
+      false,
+      // Enable Public Key Pinning bypass for local trust anchors.
+      true,
+      // Optional network thread priority.
+      base::Optional<double>());
+
+  net::URLRequestContextBuilder builder;
+  net::NetLog net_log;
+  config.ConfigureURLRequestContextBuilder(&builder, &net_log);
+  // Set a ProxyConfigService to avoid DCHECK failure when building.
+  builder.set_proxy_config_service(
+      std::make_unique<net::ProxyConfigServiceFixed>(
+          net::ProxyConfigWithAnnotation::CreateDirect()));
+  std::unique_ptr<net::URLRequestContext> context(builder.Build());
+  const net::HttpNetworkSession::Params* params =
+      context->GetNetworkSessionParams();
+
+  EXPECT_TRUE(params->quic_race_stale_dns_on_connection);
+}
+
 TEST(URLRequestContextConfigTest, SetQuicHostWhitelist) {
   base::test::ScopedTaskEnvironment scoped_task_environment_(
       base::test::ScopedTaskEnvironment::MainThreadType::IO);