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// Copyright 2024 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_FIELD_TRIAL_INTERNALS_UTILS_H_
#define COMPONENTS_VARIATIONS_FIELD_TRIAL_INTERNALS_UTILS_H_
#include <vector>
#include "base/component_export.h"
#include "base/containers/span.h"
#include "base/metrics/field_trial.h"
#include "base/time/time.h"
class PrefService;
class PrefRegistrySimple;
namespace variations {
struct ClientFilterableState;
class Study;
class VariationsSeed;
class EntropyProviders;
// This file supports temporary forcing of field trials through the
// chrome://field-trial-internals page.
// Forced trial expiration:
// When field trials are forced with field-trial-internals, they remain active
// for a limited time. After 3 days, or 3 Chrome restarts, forced field trials
// are disabled. Note however that forced trials have their expirations
// refreshed if the field-trial-internals page is visited again before
// they are expired.
// In summary, all field trial overrides share the same expiration, and that
// expiration is always 3 days / restarts when visiting the
// field-trial-internals page.
// Upon restart, we check whether the forced trials should
// be honored.
// How long before a temporary field trial expires.
inline constexpr base::TimeDelta kManualForceFieldTrialDuration = base::Days(3);
// How many Chrome restarts before the temporary field trial override expires.
inline constexpr int kChromeStartCountBeforeResetForcedFieldTrials = 3;
// The name of a study and its groups.
struct COMPONENT_EXPORT(VARIATIONS) StudyGroupNames {
StudyGroupNames();
explicit StudyGroupNames(const Study& study);
~StudyGroupNames();
StudyGroupNames(const StudyGroupNames&);
StudyGroupNames& operator=(const StudyGroupNames&);
// Name of the study.
std::string name;
// Name of the groups in the study.
std::vector<std::string> groups;
};
COMPONENT_EXPORT(VARIATIONS)
void RegisterFieldTrialInternalsPrefs(PrefRegistrySimple& registry);
// Called at startup to override field trials which were overridden with
// `SetTemporaryTrialOverrides`.
COMPONENT_EXPORT(VARIATIONS)
void ForceTrialsAtStartup(PrefService& prefs);
// Sets the list of field trials which will be enabled by override upon the next
// restart. Returns false if the current set of trial overrides already in
// effect match `override_groups`, and therefore no restart is necessary.
COMPONENT_EXPORT(VARIATIONS)
bool SetTemporaryTrialOverrides(
PrefService& local_state,
base::span<std::pair<std::string, std::string>> override_groups);
// Returns the set of unexpired field trial overrides. If any exist, their
// expiration is reset. `requires_restart` is set to whether overrides have
// changed since the last restart, and therefore are not yet in effect.
// This is used when populating chrome://field-trial-internals.
COMPONENT_EXPORT(VARIATIONS)
base::flat_map<std::string, std::string> RefreshAndGetFieldTrialOverrides(
const std::vector<variations::StudyGroupNames>& available_studies,
PrefService& local_state,
bool& requires_restart);
// Returns the study and groups that could potentially be forced.
// Due to a deficiency in how studies are forced, studies which use layers
// may not be forcable, and therefore not returned here. If the layer member
// associated with the study is active, it will be available to force.
COMPONENT_EXPORT(VARIATIONS)
std::vector<StudyGroupNames> GetStudiesAvailableToForce(
VariationsSeed seed,
const EntropyProviders& entropy_providers,
const ClientFilterableState& client_filterable_state);
} // namespace variations
#endif // COMPONENTS_VARIATIONS_FIELD_TRIAL_INTERNALS_UTILS_H_
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