Add a ScopedFeatureList class for testing and start using it.

components/flags_ui/flags_state_unittest.cc

 // Copyright 2015 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 "components/flags_ui/flags_state.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/bind.h"
 #include "base/feature_list.h"
 #include "base/format_macros.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/scoped_feature_list.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "components/flags_ui/feature_entry.h"
 #include "components/flags_ui/flags_ui_pref_names.h"
 #include "components/flags_ui/flags_ui_switches.h"
 #include "components/flags_ui/pref_service_flags_storage.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/variations/variations_associated_data.h"
 #include "grit/components_strings.h"
@@ skipping 279 matching lines @@
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
 
   // Select the only one variation.
   flags_state_->SetFeatureEntryEnabled(&flags_storage_, entry.NameForOption(2),
                                        true);
   flags_state_->RegisterAllFeatureVariationParameters(&flags_storage_,
                                                       feature_list.get());
 
   // Set the feature_list as the main instance so that
   // variations::GetVariationParamValueByFeature below works.
-  base::FeatureList::ClearInstanceForTesting();
-  base::FeatureList::SetInstance(std::move(feature_list));
+  base::test::ScopedFeatureList scoped_feature_list;
+  scoped_feature_list.InitWithFeatureList(std::move(feature_list));
 
   // The param should have the value predefined in this variation.
   EXPECT_EQ(kTestParamValue,
             variations::GetVariationParamValue(kTestTrial, kTestParam));
 
   // The value should be associated also via the name of the feature.
   EXPECT_EQ(kTestParamValue, variations::GetVariationParamValueByFeature(
                                   kTestFeature2, kTestParam));
 }
 
@@ skipping 447 matching lines @@
                                       &supported_entries, &unsupported_entries,
                                       base::Bind(&SkipFeatureEntry));
   // All |kEntries| except for |kFlags3| should be supported.
   EXPECT_EQ(7u, supported_entries.GetSize());
   EXPECT_EQ(1u, unsupported_entries.GetSize());
   EXPECT_EQ(arraysize(kEntries),
             supported_entries.GetSize() + unsupported_entries.GetSize());
 }
 
 }  // namespace flags_ui