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// Copyright 2017 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.
#ifndef COMPONENTS_VARIATIONS_SYNTHETIC_TRIAL_REGISTRY_H_
#define COMPONENTS_VARIATIONS_SYNTHETIC_TRIAL_REGISTRY_H_
#include <vector>
#include "base/feature_list.h"
#include "base/observer_list.h"
#include "components/variations/synthetic_trials.h"
namespace metrics {
class MetricsServiceAccessor;
} // namespace metrics
namespace variations {
struct ActiveGroupId;
class FieldTrialsProvider;
class FieldTrialsProviderTest;
class SyntheticTrialRegistryTest;
namespace internal {
extern const base::Feature kExternalExperimentAllowlist;
} // namespace internal
class SyntheticTrialRegistry {
public:
// Constructor that specifies whether the SyntheticTrialRegistry should use
// an allowlist for external experiments. Some embedders such as WebLayer
// do not run as Chrome and do not use the allowlist.
// Note: The allowlist is enabled only if |kExternalExperimentAllowlist| is
// also enabled, even if the parameter value is true. The default constructor
// defaults to the feature state.
explicit SyntheticTrialRegistry(bool enable_external_experiment_allowlist);
SyntheticTrialRegistry();
~SyntheticTrialRegistry();
// Adds an observer to be notified when the synthetic trials list changes.
void AddSyntheticTrialObserver(SyntheticTrialObserver* observer);
// Removes an existing observer of synthetic trials list changes.
void RemoveSyntheticTrialObserver(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.
//
// When |enable_external_experiment_allowlist| is true, 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.
//
// When |enable_external_experiment_allowlist| is false, |fallback_study_name|
// will be used as the trial name for all provided experiment ids.
//
// 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::string& fallback_study_name,
const std::vector<int>& experiment_ids,
OverrideMode mode);
private:
friend metrics::MetricsServiceAccessor;
friend FieldTrialsProvider;
friend FieldTrialsProviderTest;
friend SyntheticTrialRegistryTest;
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest, RegisterSyntheticTrial);
FRIEND_TEST_ALL_PREFIXES(SyntheticTrialRegistryTest,
GetSyntheticFieldTrialActiveGroups);
FRIEND_TEST_ALL_PREFIXES(VariationsCrashKeysTest, BasicFunctionality);
// Registers a field trial name and group to be used to annotate a UMA report
// with a particular Chrome configuration state. A UMA report will be
// annotated with this trial group if and only if all events in the report
// were created after the trial is registered. 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.
// 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| if the allowlist is enabled, otherwise returns
// |fallback_study_name|. An empty string piece is returned when the
// experiment is not in the allowlist.
base::StringPiece GetStudyNameForExpId(const std::string& fallback_study_name,
const base::FieldTrialParams& params,
const std::string& experiment_id);
// Returns a list of synthetic field trials that are older than |time|.
void GetSyntheticFieldTrialsOlderThan(
base::TimeTicks time,
std::vector<ActiveGroupId>* synthetic_trials) const;
// Notifies observers on a synthetic trial list change.
void NotifySyntheticTrialObservers();
// Whether the allowlist is enabled. Some configurations, like WebLayer
// do not use the allowlist.
bool enable_external_experiment_allowlist_ = true;
// 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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