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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_SERVICE_VARIATIONS_FIELD_TRIAL_CREATOR_H_
#define COMPONENTS_VARIATIONS_SERVICE_VARIATIONS_FIELD_TRIAL_CREATOR_H_
#include <memory>
#include <set>
#include <string>
#include <vector>
#include "base/compiler_specific.h"
#include "base/containers/hash_tables.h"
#include "base/macros.h"
#include "base/metrics/field_trial.h"
#include "components/variations/client_filterable_state.h"
#include "components/variations/proto/study.pb.h"
#include "components/variations/seed_response.h"
#include "components/variations/service/ui_string_overrider.h"
#include "components/variations/variations_seed_store.h"
namespace variations {
class PlatformFieldTrials;
class SafeSeedManager;
class VariationsServiceClient;
// Used to setup field trials based on stored variations seed data.
class VariationsFieldTrialCreator {
public:
// Caller is responsible for ensuring that objects passed to the constructor
// stay valid for the lifetime of this object.
VariationsFieldTrialCreator(PrefService* local_state,
VariationsServiceClient* client,
std::unique_ptr<VariationsSeedStore> seed_store,
const UIStringOverrider& ui_string_overrider);
virtual ~VariationsFieldTrialCreator();
// Returns what variations will consider to be the latest country. Returns
// empty if it is not available.
std::string GetLatestCountry() const;
VariationsSeedStore* seed_store() { return seed_store_.get(); }
// Sets up field trials based on stored variations seed data. Returns whether
// setup completed successfully.
// |kEnableGpuBenchmarking|, |kEnableFeatures|, |kDisableFeatures| are
// feature controlling flags not directly accesible from variations.
// |unforcable_field_trials| contains the list of trials that can not be
// overridden.
// |variation_ids| allows for forcing ids selected in chrome://flags and/or
// specified using the command-line flag.
// |low_entropy_provider| allows for field trial randomization.
// |feature_list| contains the list of all active features for this client.
// |platform_field_trials| provides the platform specific field trial set up
// for Chrome.
// |safe_seed_manager| should be notified of the combined server and client
// state that was activated to create the field trials (only when the return
// value is true).
bool SetupFieldTrials(const char* kEnableGpuBenchmarking,
const char* kEnableFeatures,
const char* kDisableFeatures,
const std::set<std::string>& unforceable_field_trials,
const std::vector<std::string>& variation_ids,
std::unique_ptr<const base::FieldTrial::EntropyProvider>
low_entropy_provider,
std::unique_ptr<base::FeatureList> feature_list,
PlatformFieldTrials* platform_field_trials,
SafeSeedManager* safe_seed_manager);
// Returns all of the client state used for filtering studies.
// As a side-effect, may update the stored permanent consistency country.
std::unique_ptr<ClientFilterableState> GetClientFilterableStateForVersion(
const base::Version& version);
// Loads the country code to use for filtering permanent consistency studies,
// updating the stored country code if the stored value was for a different
// Chrome version. The country used for permanent consistency studies is kept
// consistent between Chrome upgrades in order to avoid annoying the user due
// to experiment churn while traveling.
std::string LoadPermanentConsistencyCountry(
const base::Version& version,
const std::string& latest_country);
// Sets the stored permanent country pref for this client.
void StorePermanentCountry(const base::Version& version,
const std::string& country);
// Records the time of the most recent successful fetch.
void RecordLastFetchTime();
// Allow the platform that is used to filter the set of active trials to be
// overridden.
void OverrideVariationsPlatform(Study::Platform platform_override);
// Overrides cached UI strings on the resource bundle once it is initialized.
void OverrideCachedUIStrings();
// Returns whether the map of the cached UI strings to override is empty.
bool IsOverrideResourceMapEmpty();
// Returns the short hardware class value used to evaluate variations hardware
// class filters. Only implemented on CrOS - returns empty string on other
// platforms.
static std::string GetShortHardwareClass();
private:
// Loads the seed from the variations store into |seed|, and records metrics
// about the loaded seed. Returns true on success, in which case |seed| will
// contain the loaded data, and |seed_data| and |base64_signature| will
// contain the raw pref values.
bool LoadSeed(VariationsSeed* seed,
std::string* seed_data,
std::string* base64_signature) WARN_UNUSED_RESULT;
// Loads the safe seed from the variations store into |seed| and updates any
// relevant fields in |client_state|. If the load succeeds, records metrics
// about the loaded seed. Returns whether the load succeeded.
bool LoadSafeSeed(VariationsSeed* seed,
ClientFilterableState* client_state) WARN_UNUSED_RESULT;
// Creates field trials based on the variations seed loaded from local state.
// If there is a problem loading the seed data, all trials specified by the
// seed may not be created. Some field trials are configured to override or
// associate with (for reporting) specific features. These associations are
// registered with |feature_list|. Returns true if trials were created
// successfully; and if so, stores the loaded variations state into the
// |safe_seed_manager|.
bool CreateTrialsFromSeed(
std::unique_ptr<const base::FieldTrial::EntropyProvider>
low_entropy_provider,
base::FeatureList* feature_list,
SafeSeedManager* safe_seed_manager);
// Overrides the string resource specified by |hash| with |str| in the
// resource bundle.
void OverrideUIString(uint32_t hash, const base::string16& str);
// Returns the seed store. Virtual for testing.
virtual VariationsSeedStore* GetSeedStore();
// Get the platform we're running on, respecting OverrideVariationsPlatform().
Study::Platform GetPlatform();
PrefService* local_state() { return seed_store_->local_state(); }
const PrefService* local_state() const { return seed_store_->local_state(); }
VariationsServiceClient* client_;
UIStringOverrider ui_string_overrider_;
std::unique_ptr<VariationsSeedStore> seed_store_;
// Tracks whether |CreateTrialsFromSeed| has been called, to ensure that it is
// called at most once.
bool create_trials_from_seed_called_;
// The application locale won't change after the startup, so we cache the
// value the first time when GetApplicationLocale() is called in the
// constructor.
std::string application_locale_;
// Indiciate if OverrideVariationsPlatform has been used to set
// |platform_override_|.
bool has_platform_override_;
// Platform to be used for variations filtering, overridding the current
// platform.
Study::Platform platform_override_;
// Caches the UI strings which need to be overridden in the resource bundle.
// These strings are cached before the resource bundle is initialized.
base::hash_map<int, base::string16> overridden_strings_map_;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(VariationsFieldTrialCreator);
};
} // namespace variations
#endif // COMPONENTS_VARIATIONS_SERVICE_VARIATIONS_FIELD_TRIAL_CREATOR_H_