Add a ScopedFeatureList class for testing and start using it.

components/ssl_config/ssl_config_service_manager_pref_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 #include <utility>
 
 #include "base/feature_list.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_feature_list.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/ssl_config/ssl_config_prefs.h"
 #include "components/ssl_config/ssl_config_service_manager.h"
 #include "components/ssl_config/ssl_config_switches.h"
 #include "net/ssl/ssl_config.h"
 #include "net/ssl/ssl_config_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 152 matching lines @@
 
   SSLConfig ssl_config;
   config_service->GetSSLConfig(&ssl_config);
   // The command-line option must not have been honored.
   EXPECT_LE(net::SSL_PROTOCOL_VERSION_TLS1, ssl_config.version_min);
 }
 
 // Tests that DHE may be re-enabled via features.
 TEST_F(SSLConfigServiceManagerPrefTest, DHEFeature) {
   // Toggle the feature.
-  base::FeatureList::ClearInstanceForTesting();
-  std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
-  feature_list->InitializeFromCommandLine("DHECiphers", std::string());
-  base::FeatureList::SetInstance(std::move(feature_list));
+  base::test::ScopedFeatureList scoped_feature_list;
+  scoped_feature_list.InitFromCommandLine("DHECiphers", std::string());
 
   TestingPrefServiceSimple local_state;
   SSLConfigServiceManager::RegisterPrefs(local_state.registry());
 
   std::unique_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_TRUE(ssl_config.dhe_enabled);
 }