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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_VARIATIONS_SYNTHETIC_TRIAL_REGISTRY_H_
#define COMPONENTS_VARIATIONS_SYNTHETIC_TRIAL_REGISTRY_H_
#include <vector>
#include <string_view>
#include "base/component_export.h"
#include "base/feature_list.h"
#include "base/gtest_prod_util.h"
#include "base/metrics/field_trial_params.h"
#include "base/observer_list.h"
#include "components/variations/synthetic_trials.h"
namespace metrics {
class MetricsServiceAccessor;
} // namespace metrics
namespace content {
class SyntheticTrialSyncer;
} // namespace content
namespace variations {
struct ActiveGroupId;
class FieldTrialsProvider;
class FieldTrialsProviderTest;
class SyntheticTrialRegistryTest;
namespace internal {
COMPONENT_EXPORT(VARIATIONS) BASE_DECLARE_FEATURE(kExternalExperimentAllowlist);
} // namespace internal
class COMPONENT_EXPORT(VARIATIONS) SyntheticTrialRegistry {
public:
SyntheticTrialRegistry();
~SyntheticTrialRegistry();
// Adds an observer to be notified when the synthetic trials list changes.
void AddObserver(SyntheticTrialObserver* observer);
// Removes an existing observer of synthetic trials list changes.
void RemoveObserver(SyntheticTrialObserver* observer);
// Specifies the mode of RegisterExternalExperiments() operation.
enum OverrideMode {
// Previously-registered external experiment ids are overridden (replaced)
// with the new list.
kOverrideExistingIds,
// Previously-registered external experiment ids are not overridden, but
// new experiment ids may be added.
kDoNotOverrideExistingIds,
};
// Registers a list of experiment ids coming from an external application.
// The input ids are in the VariationID format.
//
// The supplied ids must have corresponding entries in the
// "ExternalExperimentAllowlist" (coming via a feature param) to be applied.
// The allowlist also supplies the corresponding trial name that should be
// used for reporting to UMA.
//
// If |mode| is kOverrideExistingIds, this API clears previously-registered
// external experiment ids, replacing them with the new list (which may be
// empty). If |mode| is kDoNotOverrideExistingIds, any new ids that are not
// already registered will be added, but existing ones will not be replaced.
void RegisterExternalExperiments(const std::vector<int>& experiment_ids,
OverrideMode mode);
// Exposed publicly for testing purposes, it returns a full list of synthetic
// field trials that are either in the past or specify |kCurrentLog| as
// |annotation_mode|.
std::vector<ActiveGroupId> GetCurrentSyntheticFieldTrialsForTest() const;
private:
friend metrics::MetricsServiceAccessor;
friend FieldTrialsProvider;
friend FieldTrialsProviderTest;
friend SyntheticTrialRegistryTest;
friend content::SyntheticTrialSyncer;
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest, RegisterSyntheticTrial);
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest,
GetSyntheticFieldTrialsOlderThanSuffix);
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest,
GetSyntheticFieldTrialActiveGroups);
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest, NotifyObserver);
FRIEND_TEST_ALL_PREFIXES(VariationsCrashKeysTest, BasicFunctionality);
// Registers a field trial name and group to be used to annotate UMA and UKM
// reports with a particular Chrome configuration state.
//
// If the |trial_group|'s |annotation_mode| is set to |kNextLog|, then reports
// will be annotated with this trial group if and only if all events in the
// report were created after the trial's registration. If the
// |annotation_mode| is set to |kCurrentLog|, then reports will be annotated
// with this trial group even if there are events in the report that were
// created before this trial's registration.
//
// Only one group name may be registered at a time for a given trial name.
// Only the last group name that is registered for a given trial name will be
// recorded. The values passed in must not correspond to any real field trial
// in the code.
//
// Synthetic trials are not automatically re-registered after a restart.
//
// Note: Should not be used to replace trials that were registered with
// RegisterExternalExperiments().
void RegisterSyntheticFieldTrial(const SyntheticTrialGroup& trial_group);
// Returns the study name corresponding to |experiment_id| from the allowlist
// contained in |params|. An empty string view is returned when the
// experiment is not in the allowlist.
std::string_view GetStudyNameForExpId(const base::FieldTrialParams& params,
const std::string& experiment_id);
// Returns a list of synthetic field trials that are either (1) older than
// |time|, or (2) specify |kCurrentLog| as |annotation_mode|. The trial and
// group names are suffixed with |suffix| before being hashed.
void GetSyntheticFieldTrialsOlderThan(
base::TimeTicks time,
std::vector<ActiveGroupId>* synthetic_trials,
std::string_view suffix = "") const;
// SyntheticTrialSyncer needs to know all current synthetic trial
// groups after launching new child processes.
const std::vector<SyntheticTrialGroup>& GetSyntheticTrialGroups() const {
return synthetic_trial_groups_;
}
// Notifies observers on a synthetic trial list change.
void NotifySyntheticTrialObservers(
const std::vector<SyntheticTrialGroup>& trials_updated,
const std::vector<SyntheticTrialGroup>& trials_removed);
// Field trial groups that map to Chrome configuration states.
std::vector<SyntheticTrialGroup> synthetic_trial_groups_;
// List of observers of |synthetic_trial_groups_| changes.
base::ObserverList<SyntheticTrialObserver>::Unchecked
synthetic_trial_observer_list_;
};
} // namespace variations
#endif // COMPONENTS_VARIATIONS_SYNTHETIC_TRIAL_REGISTRY_H_
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