Extend VariationParamsManager to support feature associations.

components/variations/variations_params_manager.cc

+// Copyright 2016 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/variations/variations_params_manager.h"
+
+#include <utility>
+
+#include "base/feature_list.h"
+#include "base/metrics/field_trial.h"
+#include "base/test/scoped_feature_list.h"
+#include "components/variations/variations_associated_data.h"
+
+namespace variations {
+

[Alexei Svitkine (slow), 2016/09/12 16:54:13]

Nit: Remove empty line

[jkrcal, 2016/09/23 13:40:09]

Done.

+namespace testing {
+
+namespace {
+
+const char kGroupTesting[] = "Testing";
+
+}  // namespace
+
+VariationParamsManager::VariationParamsManager()
+    : field_trial_list_(new base::FieldTrialList(nullptr)),
+      scoped_feature_list_(new base::test::ScopedFeatureList()) {}
+
+VariationParamsManager::VariationParamsManager(
+    const std::string& trial_name,
+    const std::map<std::string, std::string>& param_values,
+    const std::map<std::string, std::string>& param_features)
+    : VariationParamsManager() {
+  SetVariationParams(trial_name, param_values, param_features);
+}
+
+VariationParamsManager::~VariationParamsManager() {
+  ClearAllVariationIDs();
+  ClearAllVariationParams();
+}
+
+void VariationParamsManager::SetVariationParams(
+    const std::string& trial_name,
+    const std::map<std::string, std::string>& param_values,
+    const std::map<std::string, std::string>& param_features) {
+  variations::AssociateVariationParams(trial_name, kGroupTesting, param_values);
+  base::FieldTrial* field_trial =
+      base::FieldTrialList::CreateFieldTrial(trial_name, kGroupTesting);
+
+  std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
+  for (auto& pair : param_features) {
+    feature_list->RegisterFieldTrialOverride(
+              pair.second /* name of the feature */,
+              base::FeatureList::OverrideState::OVERRIDE_ENABLE_FEATURE,
+              field_trial);
+  }
+
+  scoped_feature_list_->InitWithFeatureList(std::move(feature_list));
+}
+
+void VariationParamsManager::ClearAllVariationIDs() {
+  variations::testing::ClearAllVariationIDs();
+}
+
+void VariationParamsManager::ClearAllVariationParams() {
+  variations::testing::ClearAllVariationParams();
+  // When the scoped feature list is destroyed, it puts back the original
+  // feature list that was there when InitWithFeatureList() was called.
+  scoped_feature_list_.reset(new base::test::ScopedFeatureList());
+}
+
+}  // namespace testing
+

[Alexei Svitkine (slow), 2016/09/12 16:54:13]

Nit: Remove empty line

[jkrcal, 2016/09/23 13:40:09]

Done.

+}  // namespace variations