Disable the TLS version fallback.

components/ssl_config/ssl_config_service_manager_pref_unittest.cc

Index: components/ssl_config/ssl_config_service_manager_pref_unittest.cc
diff --git a/components/ssl_config/ssl_config_service_manager_pref_unittest.cc b/components/ssl_config/ssl_config_service_manager_pref_unittest.cc
index 72b881809acad96d1736a1234a7ad7956981eaab..c15e72b067492b1d3c9da2a09c5c2c4cfa171d94 100644
--- a/components/ssl_config/ssl_config_service_manager_pref_unittest.cc
+++ b/components/ssl_config/ssl_config_service_manager_pref_unittest.cc
@@ -4,7 +4,11 @@
 
 #include "components/ssl_config/ssl_config_service_manager.h"
 
+#include <utility>
+
+#include "base/feature_list.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/values.h"
@@ -173,3 +177,49 @@ TEST_F(SSLConfigServiceManagerPrefTest, NoSSL3) {
   // The command-line option must not have been honored.
   EXPECT_LE(net::SSL_PROTOCOL_VERSION_TLS1, ssl_config.version_min);
 }
+
+// Tests that fallback beyond TLS 1.0 cannot be re-enabled.
+TEST_F(SSLConfigServiceManagerPrefTest, NoTLS1Fallback) {
+  scoped_refptr<TestingPrefStore> local_state_store(new TestingPrefStore());
+
+  TestingPrefServiceSimple local_state;
+  local_state.SetUserPref(ssl_config::prefs::kSSLVersionFallbackMin,
+                          new base::StringValue("tls1"));
+  SSLConfigServiceManager::RegisterPrefs(local_state.registry());
+
+  scoped_ptr<SSLConfigServiceManager> config_manager(
+      SSLConfigServiceManager::CreateDefaultManager(
+          &local_state, base::ThreadTaskRunnerHandle::Get()));
+  ASSERT_TRUE(config_manager.get());
+  scoped_refptr<SSLConfigService> config_service(config_manager->Get());
+  ASSERT_TRUE(config_service.get());
+
+  SSLConfig ssl_config;
+  config_service->GetSSLConfig(&ssl_config);
+  // The command-line option must not have been honored.
+  EXPECT_EQ(net::SSL_PROTOCOL_VERSION_TLS1_2, ssl_config.version_fallback_min);
+}
+
+// Tests that the TLS 1.1 fallback may be re-enabled via features.
+TEST_F(SSLConfigServiceManagerPrefTest, TLSFallbackFeature) {
+  // Toggle the feature.
+  base::FeatureList::ClearInstanceForTesting();
+  scoped_ptr<base::FeatureList> feature_list(new base::FeatureList);
+  feature_list->InitializeFromCommandLine("SSLVersionFallbackTLSv1.1",
+                                          std::string());
+  base::FeatureList::SetInstance(std::move(feature_list));
+
+  TestingPrefServiceSimple local_state;
+  SSLConfigServiceManager::RegisterPrefs(local_state.registry());
+
+  scoped_ptr<SSLConfigServiceManager> config_manager(
+      SSLConfigServiceManager::CreateDefaultManager(
+          &local_state, base::ThreadTaskRunnerHandle::Get()));
+  scoped_refptr<SSLConfigService> config_service(config_manager->Get());
+  ASSERT_TRUE(config_service.get());
+
+  // The feature should have switched the default version_fallback_min value.
+  SSLConfig ssl_config;
+  config_service->GetSSLConfig(&ssl_config);
+  EXPECT_EQ(net::SSL_PROTOCOL_VERSION_TLS1_1, ssl_config.version_fallback_min);
+}