Implement field trial for NPN.

Implement field trial for Next Protocol Negotiation to allow for controlled
deprecation.  Default (in absense of field trial) is enabled.

BUG=526713

Review URL: https://codereview.chromium.org/1429683003

Cr-Commit-Position: refs/heads/master@{#356716}

5 files changed, 57 insertions, 1 deletions

diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 14f405c..e13d23c 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -155,6 +155,11 @@ const char kSpdyFieldTrialParametrizedPrefix[] = "Parametrized";
 // determined by the operating system.
 const char kNetworkQualityEstimatorFieldTrialName[] = "NetworkQualityEstimator";
 
+// Field trial for NPN.
+const char kNpnTrialName[] = "NPN";
+const char kNpnTrialEnabledGroupNamePrefix[] = "Enable";
+const char kNpnTrialDisabledGroupNamePrefix[] = "Disable";
+
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 void ObserveKeychainEvents() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -884,6 +889,9 @@ void IOThread::InitializeNetworkOptions(const base::CommandLine& command_line) {
 
   ConfigureTCPFastOpen(command_line);
 
+  ConfigureNPNGlobals(base::FieldTrialList::FindFullName(kNpnTrialName),
+                      globals_);
+
   // TODO(rch): Make the client socket factory a per-network session
   // instance, constructed from a NetworkSession::Params, to allow us
   // to move this option to IOThread::Globals &
@@ -902,6 +910,7 @@ void IOThread::ConfigureTCPFastOpen(const base::CommandLine& command_line) {
   net::CheckSupportAndMaybeEnableTCPFastOpen(always_enable_if_supported);
 }
 
+// static
 void IOThread::ConfigureSpdyGlobals(
     const base::CommandLine& command_line,
     base::StringPiece spdy_trial_group,
@@ -964,6 +973,16 @@ void IOThread::ConfigureSpdyGlobals(
   globals->next_protos.push_back(net::kProtoHTTP11);
 }
 
+// static
+void IOThread::ConfigureNPNGlobals(base::StringPiece npn_trial_group,
+                                   IOThread::Globals* globals) {
+  if (npn_trial_group.starts_with(kNpnTrialEnabledGroupNamePrefix)) {
+    globals->enable_npn.set(true);
+  } else if (npn_trial_group.starts_with(kNpnTrialDisabledGroupNamePrefix)) {
+    globals->enable_npn.set(false);
+  }
+}
+
 void IOThread::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterStringPref(prefs::kAuthSchemes,
                                "basic,digest,ntlm,negotiate");
@@ -1052,6 +1071,8 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
   globals.alternative_service_probability_threshold.CopyToIfSet(
       &params->alternative_service_probability_threshold);
 
+  globals.enable_npn.CopyToIfSet(&params->enable_npn);
+
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
   globals.enable_quic_for_proxies.CopyToIfSet(&params->enable_quic_for_proxies);
   globals.quic_always_require_handshake_confirmation.CopyToIfSet(
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index 33291d6..0b3a688 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -188,6 +188,8 @@ class IOThread : public content::BrowserThreadDelegate {
     Optional<bool> use_alternative_services;
     Optional<double> alternative_service_probability_threshold;
 
+    Optional<bool> enable_npn;
+
     Optional<bool> enable_quic;
     Optional<bool> enable_quic_for_proxies;
     Optional<bool> enable_quic_port_selection;
@@ -290,6 +292,10 @@ class IOThread : public content::BrowserThreadDelegate {
                                    const VariationParameters& quic_trial_params,
                                    Globals* globals);
 
+  // Configures NPN in |globals| based on the field trial group.
+  static void ConfigureNPNGlobals(base::StringPiece npn_trial_group,
+                                  Globals* globals);
+
   // Global state must be initialized on the IO thread, then this
   // method must be invoked on the UI thread.
   void InitSystemRequestContext();
diff --git a/chrome/browser/io_thread_unittest.cc b/chrome/browser/io_thread_unittest.cc
index 4430306..26bf872 100644
--- a/chrome/browser/io_thread_unittest.cc
+++ b/chrome/browser/io_thread_unittest.cc
@@ -40,6 +40,11 @@ class IOThreadPeer {
                                    spdy_trial_params, globals);
   }
 
+  static void ConfigureNPNGlobals(base::StringPiece npn_trial_group,
+                                  IOThread::Globals* globals) {
+    IOThread::ConfigureNPNGlobals(npn_trial_group, globals);
+  }
+
   static void InitializeNetworkSessionParamsFromGlobals(
       const IOThread::Globals& globals,
       net::HttpNetworkSession::Params* params) {
@@ -68,6 +73,10 @@ class IOThreadTest : public testing::Test {
                                        field_trial_params_, &globals_);
   }
 
+  void ConfigureNPNGlobals() {
+    IOThreadPeer::ConfigureNPNGlobals(field_trial_group_, &globals_);
+  }
+
   void InitializeNetworkSessionParams(net::HttpNetworkSession::Params* params) {
     IOThreadPeer::InitializeNetworkSessionParamsFromGlobals(globals_, params);
   }
@@ -137,6 +146,22 @@ TEST_F(IOThreadTest, SpdyCommandLineUseSpdyOff) {
   EXPECT_EQ(0u, globals_.next_protos.size());
 }
 
+TEST_F(IOThreadTest, NPNFieldTrialEnabled) {
+  field_trial_group_ = "Enable-experiment";
+  ConfigureNPNGlobals();
+  net::HttpNetworkSession::Params params;
+  InitializeNetworkSessionParams(&params);
+  EXPECT_TRUE(params.enable_npn);
+}
+
+TEST_F(IOThreadTest, NPNFieldTrialDisabled) {
+  field_trial_group_ = "Disable-holdback";
+  ConfigureNPNGlobals();
+  net::HttpNetworkSession::Params params;
+  InitializeNetworkSessionParams(&params);
+  EXPECT_FALSE(params.enable_npn);
+}
+
 TEST_F(IOThreadTest, DisableQuicByDefault) {
   ConfigureQuicGlobals();
   net::HttpNetworkSession::Params params;
diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc
index 736d5a9..0d58756 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -93,6 +93,7 @@ HttpNetworkSession::Params::Params()
       time_func(&base::TimeTicks::Now),
       use_alternative_services(false),
       alternative_service_probability_threshold(1),
+      enable_npn(true),
       enable_quic(false),
       enable_quic_for_proxies(false),
       enable_quic_port_selection(true),
@@ -330,7 +331,7 @@ void HttpNetworkSession::GetAlpnProtos(NextProtoVector* alpn_protos) const {
 }
 
 void HttpNetworkSession::GetNpnProtos(NextProtoVector* npn_protos) const {
-  if (HttpStreamFactory::spdy_enabled()) {
+  if (HttpStreamFactory::spdy_enabled() && params_.enable_npn) {
     *npn_protos = next_protos_;
     DisableHTTP2(npn_protos);
   } else {
diff --git a/net/http/http_network_session.h b/net/http/http_network_session.h
index 0075154..20ee21e 100644
--- a/net/http/http_network_session.h
+++ b/net/http/http_network_session.h
@@ -111,6 +111,9 @@ class NET_EXPORT HttpNetworkSession
     // than this value.
     double alternative_service_probability_threshold;
 
+    // Enables NPN support.  Note that ALPN is always enabled.
+    bool enable_npn;
+
     // Enables QUIC support.
     bool enable_quic;
     // Enables QUIC for proxies.