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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_READALOUD_ANDROID_SYNTHETIC_TRIAL_H_
#define CHROME_BROWSER_READALOUD_ANDROID_SYNTHETIC_TRIAL_H_
#include <memory>
#include <string>
#include "base/feature_list.h"
#include "base/memory/raw_ptr.h"
#include "base/metrics/field_trial.h"
#include "components/prefs/pref_service.h"
namespace readaloud {
/**
* This class registers a synthetic field trial based on an ordinary FieldTrial
* to allow custom activation criteria.
*/
class SyntheticTrial {
public:
/**
* Remove any reactivation signals for trials whose base trials have changed.
* Feature list must be initialized before calling.
*/
static void ClearStalePrefs();
/**
* Create a SyntheticTrial. Feature list should be initialized before calling.
*
* Can't be used with features or trials whose names include "|||" as this is
* used internally as a separator.
*
* Reactivates the synthetic trial associated with `feature_name` if the
* current base trial matches what was stored when the synthetic trial was
* previously activated.
* @param feature_name Feature controlled by the base trial, used to retrieve
* base trial name and group name.
* @param trial_suffix String to append to the synthetic trial name to
* distinguish it from the base trial. Must be non-empty.
*/
static std::unique_ptr<SyntheticTrial> Create(
const std::string& feature_name,
const std::string& trial_suffix);
SyntheticTrial(const SyntheticTrial& other) = delete;
SyntheticTrial& operator=(const SyntheticTrial& other) = delete;
/**
* Perform first-time registration of the trial.
*
* If the base trial controlling the feature specified by
* `target_feature_name` has trial name "BaseTrial" and group name
* "BaseGroup", the synthetic trial will be named "BaseTrial"+`trial_suffix`
* and it will use the same group name "BaseGroup".
*
* This function sets a pref so that the trial will be reactivated in future
* sessions.
*
* This method only registers the trial the first time it is called.
* Subsequent calls have no effect.
*/
void Activate();
private:
friend std::unique_ptr<SyntheticTrial> std::make_unique<SyntheticTrial>(
const std::string&,
const std::string&,
base::FieldTrial*&);
SyntheticTrial(const std::string& feature_name,
const std::string& trial_suffix,
base::FieldTrial* trial);
std::string pref_key() const;
PrefService* prefs();
const std::string feature_name_;
const std::string suffix_;
bool synthetic_trial_active_ = false;
// Owned by base::FieldTrialList singleton which lives for the lifetime of the
// browser process.
raw_ptr<base::FieldTrial> base_trial_;
};
} // namespace readaloud
#endif // CHROME_BROWSER_READALOUD_ANDROID_SYNTHETIC_TRIAL_H_
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