components/omnibox/browser/omnibox_field_trial.h

// Copyright 2014 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_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_
#define COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_

#include <stddef.h>
#include <stdint.h>

#include <map>
#include <string>
#include <utility>
#include <vector>

#include "base/feature_list.h"
#include "base/metrics/field_trial_params.h"
#include "components/omnibox/browser/autocomplete_match_type.h"
#include "components/omnibox/browser/autocomplete_provider.h"
#include "components/omnibox/common/omnibox_features.h"
#include "third_party/metrics_proto/omnibox_event.pb.h"
#include "third_party/omnibox_proto/entity_info.pb.h"

namespace base {
class TimeDelta;
}  // namespace base

// The set of parameters customizing the HUP scoring.
struct HUPScoringParams {
  // A set of parameters describing how to cap a given count score.  First,
  // we apply a half-life based decay of the given count and then find the
  // maximum relevance score based on the decay factor or counts specified
  // in the corresponding bucket list. See comment on |buckets_| for details.
  class ScoreBuckets {
   public:
    // Stores the max relevance at each count/decay factor threshold.
    typedef std::pair<double, int> CountMaxRelevance;

    ScoreBuckets();
    ScoreBuckets(const ScoreBuckets& other);
    ~ScoreBuckets();

    // Computes a half-life time decay given the |elapsed_time|.
    double HalfLifeTimeDecay(const base::TimeDelta& elapsed_time) const;

    int relevance_cap() const { return relevance_cap_; }
    void set_relevance_cap(int relevance_cap) {
      relevance_cap_ = relevance_cap;
    }

    int half_life_days() const { return half_life_days_; }
    void set_half_life_days(int half_life_days) {
      half_life_days_ = half_life_days;
    }

    bool use_decay_factor() const { return use_decay_factor_; }
    void set_use_decay_factor(bool use_decay_factor) {
      use_decay_factor_ = use_decay_factor;
    }

    std::vector<CountMaxRelevance>& buckets() { return buckets_; }
    const std::vector<CountMaxRelevance>& buckets() const { return buckets_; }

    // Estimates dynamic memory usage.
    // See base/trace_event/memory_usage_estimator.h for more info.
    size_t EstimateMemoryUsage() const;

   private:
    // History matches with relevance score greater or equal to |relevance_cap_|
    // are not affected by this experiment.
    // Set to -1, if there is no relevance cap in place and all matches are
    // subject to demotion.
    int relevance_cap_;

    // Half life time for a decayed count as measured since the last visit.
    // Set to -1 if not used.
    int half_life_days_;

    // The relevance score caps at successively decreasing threshold values.
    // The thresholds are either decayed counts or decay factors, depending on
    // the value of |use_decay_factor_|.
    //
    // Consider this example specifying the decayed counts:
    //   [(1, 1000), (0.5, 500), (0, 100)]
    // If decayed count is 2 (which is >= 1), the corresponding match's maximum
    // relevance will be capped at 1000.  In case of 0.5, the score is capped
    // at 500.  Anything below 0.5 is capped at 100.
    //
    // This list is sorted by the pair's first element in descending order.
    std::vector<CountMaxRelevance> buckets_;

    // True when the bucket thresholds are decay factors rather than counts.
    bool use_decay_factor_;
  };

  HUPScoringParams() = default;

  // Estimates dynamic memory usage.
  // See base/trace_event/memory_usage_estimator.h for more info.
  size_t EstimateMemoryUsage() const;

  ScoreBuckets typed_count_buckets;

  // Used only when the typed count is 0.
  ScoreBuckets visited_count_buckets;
};

namespace OmniboxFieldTrial {

// A mapping that contains multipliers indicating that matches of the
// specified type should have their relevance score multiplied by the
// given number.  Omitted types are assumed to have multipliers of 1.0.
typedef std::map<AutocompleteMatchType::Type, float> DemotionMultipliers;

// A vector that maps from the number of matching pages to the document
// specificity score used in HistoryQuick provider / ScoredHistoryMatch
// scoring. The vector is sorted by the size_t (the number of matching pages).
// If an entry is omitted, the appropriate value is assumed to be the one in
// the later bucket.  For example, with a vector containing {{1, 2.0},
// {3, 1.5}}, the score for 2 is inferred to be 1.5.  Values beyond the
// end of the vector are assumed to have scores of 1.0.
typedef std::vector<std::pair<size_t, double>> NumMatchesScores;

// ---------------------------------------------------------
// For any experiment that's part of the bundled omnibox field trial.

// Returns a bitmap containing AutocompleteProvider::Type values
// that should be disabled in AutocompleteController.
int GetDisabledProviderTypes();

// Returns whether the user is in any dynamic field trial where the
// group has a the prefix |group_prefix|.
bool HasDynamicFieldTrialGroupPrefix(const char* group_prefix);

// ---------------------------------------------------------
// For the suggest field trial.

// Populates |field_trial_hash| with hashes of the active suggest field trial
// names, if any.
void GetActiveSuggestFieldTrialHashes(std::vector<uint32_t>* field_trial_hash);

// ---------------------------------------------------------
// For experiments related to the number of suggestions shown.

// If the user is in an experiment group that specifies the max results for a
// particular provider, returns the limit. Otherwise returns the default limit.
size_t GetProviderMaxMatches(AutocompleteProvider::Type provider);

// Returns whether the feature to limit the number of shown URL matches
// is enabled.
bool IsMaxURLMatchesFeatureEnabled();

// Returns the maximum number of URL matches that should be allowed within
// the Omnibox if there are search-type matches available to replace them.
// If the capping feature is not enabled, or the parameter cannot be
// parsed, it returns 0.
size_t GetMaxURLMatches();

// ---------------------------------------------------------
// For the HistoryURL provider new scoring experiment that is part of the
// bundled omnibox field trial.

// Initializes the HUP |scoring_params| based on the active HUP scoring
// experiment.
void GetDefaultHUPScoringParams(HUPScoringParams* scoring_params);
void GetExperimentalHUPScoringParams(HUPScoringParams* scoring_params);

// ---------------------------------------------------------
// For the HQPBookmarkValue experiment that's part of the
// bundled omnibox field trial.

// Returns the value an untyped visit to a bookmark should receive.
// Compare this value with the default of 1 for non-bookmarked untyped
// visits to pages and the default of 20 for typed visits.  Returns
// 10 if the bookmark value experiment isn't active.
float HQPBookmarkValue();

// ---------------------------------------------------------
// For the HQPAllowMatchInTLD experiment that's part of the
// bundled omnibox field trial.

// Returns true if HQP should allow an input term to match in the
// top level domain (e.g., .com) of a URL.  Returns false if the
// allow match in TLD experiment isn't active.
bool HQPAllowMatchInTLDValue();

// ---------------------------------------------------------
// For the HQPAllowMatchInScheme experiment that's part of the
// bundled omnibox field trial.

// Returns true if HQP should allow an input term to match in the
// scheme (e.g., http://) of a URL.  Returns false if the allow
// match in scheme experiment isn't active.
bool HQPAllowMatchInSchemeValue();

// ---------------------------------------------------------
// For SearchProvider related experiments.

// Returns how the search provider should poll Suggest. Currently, we support
// measuring polling delay from the last keystroke or last suggest request.
void GetSuggestPollingStrategy(bool* from_last_keystroke,
                               int* polling_delay_ms);

// ---------------------------------------------------------
// For HQP scoring related experiments to control the topicality and scoring
// ranges of relevancy scores.

// Returns the scoring buckets for HQP experiments. Returns an empty string
// if scoring buckets are not specified in the field trial. Scoring buckets
// are stored in string form giving mapping from (topicality_score,
// frequency_score) to final relevance score. Please see GetRelevancyScore()
// under chrome/browser/history::ScoredHistoryMatch for details.
std::string HQPExperimentalScoringBuckets();

// Returns the topicality threshold for HQP experiments. Returns a default
// value of 0.5 if no threshold is specified in the field trial.
float HQPExperimentalTopicalityThreshold();

// ---------------------------------------------------------
// For experiment to limit HQP url indexing that's part of the bundled
// omnibox field trial.

// Returns the maximum number of history urls to index for HQP at the startup.
// Note: this limit is only applied at startup and more urls can be indexed
// during the session. Returns -1 if limit is not set by trials.
int MaxNumHQPUrlsIndexedAtStartup();

// ---------------------------------------------------------
// For the HQPFixFrequencyScoring experiment that's part of the
// bundled omnibox field trial.

// Returns the number of visits HQP should use when computing frequency
// scores.  Returns 10 if the experiment isn't active.
size_t HQPMaxVisitsToScore();

// Returns the score that should be given to typed transitions.  (The score
// of non-typed transitions is 1.)  Returns 1.5 if the experiment isn't
// active.
float HQPTypedValue();

// Returns NumMatchesScores; see comment by the declaration of it.
// If the experiment isn't active, returns an NumMatchesScores of
// {{1, 3}, {2, 2.5}, {3, 2}, {4, 1.5}}.
NumMatchesScores HQPNumMatchesScores();

// ---------------------------------------------------------
// For the HQPNumTitleWords experiment that's part of the
// bundled omnibox field trial.

// Returns the number of title words that are allowed to contribute
// to the topicality score.  Words later in the title are ignored.
// Returns 20 as a default if the experiment isn't active.
size_t HQPNumTitleWordsToAllow();

// ---------------------------------------------------------
// For the replace HUP experiment that's part of the bundled omnibox field
// trial.

// Returns whether HistoryQuick provider (HQP) should attempt to score
// suggestions also with a HistoryURL-provider-like (HUP-like) mode, and
// assign suggestions the max of this score and the normal score.
// Returns false if the experiment isn't active.
bool HQPAlsoDoHUPLikeScoring();

// Returns whether HistoryURL provider (HUP) should search its database for
// URLs and suggest them.  If false, HistoryURL provider merely creates the
// URL-what-you-typed match when appropriate.  Return true if the experiment
// isn't active.
bool HUPSearchDatabase();

// ---------------------------------------------------------
// For UI experiments.

// On Device Suggestions feature and its helper functions.
// TODO(crbug.com/40218594): clean up head suggest flags once crbug.com/1307005
// no longer happens.
bool IsOnDeviceHeadSuggestEnabledForIncognito();
bool IsOnDeviceHeadSuggestEnabledForNonIncognito();
bool IsOnDeviceHeadSuggestEnabledForAnyMode();
bool IsOnDeviceHeadSuggestEnabledForLocale(const std::string& locale);
bool IsOnDeviceTailSuggestEnabled(const std::string& locale);
bool ShouldEncodeLeadingSpaceForOnDeviceTailSuggest();
bool ShouldApplyOnDeviceHeadModelSelectionFix();
// Functions can be used in both non-incognito and incognito.
std::string OnDeviceHeadModelLocaleConstraint(bool is_incognito);

// ---------------------------------------------------------
// Clipboard URL suggestions:

// The parameter "ClipboardURLMaximumAge" doesn't live in this file; instead
// it lives in
// components/open_from_clipboard/clipboard_recent_content.cc.
// Please see ClipboardRecentContent::MaximumAgeOfClipboard() for the usage
// of it.  The parameter cannot live here because that component cannot
// include this component, else there would be a circular dependency.

// ---------------------------------------------------------
// Exposed publicly for the sake of unittests.
extern const char kBundledExperimentFieldTrialName[];
// Rule names used by the bundled experiment.
extern const char kDisableProvidersRule[];
extern const char kSearchHistoryRule[];
extern const char kDemoteByTypeRule[];
extern const char kHQPBookmarkValueRule[];
extern const char kHQPTypedValueRule[];
extern const char kHQPAllowMatchInTLDRule[];
extern const char kHQPAllowMatchInSchemeRule[];
extern const char kMeasureSuggestPollingDelayFromLastKeystrokeRule[];
extern const char kSuggestPollingDelayMsRule[];
extern const char kHQPMaxVisitsToScoreRule[];
extern const char kHQPNumMatchesScoresRule[];
extern const char kHQPNumTitleWordsRule[];
extern const char kHQPAlsoDoHUPLikeScoringRule[];
extern const char kHUPSearchDatabaseRule[];
extern const char kPreventUWYTDefaultForNonURLInputsRule[];
extern const char kHQPAllowDupMatchesForScoringRule[];
extern const char kEmphasizeTitlesRule[];

// Parameter names used by the HUP new scoring experiments.
extern const char kHUPNewScoringTypedCountRelevanceCapParam[];
extern const char kHUPNewScoringTypedCountHalfLifeTimeParam[];
extern const char kHUPNewScoringTypedCountScoreBucketsParam[];
extern const char kHUPNewScoringTypedCountUseDecayFactorParam[];
extern const char kHUPNewScoringVisitedCountRelevanceCapParam[];
extern const char kHUPNewScoringVisitedCountHalfLifeTimeParam[];
extern const char kHUPNewScoringVisitedCountScoreBucketsParam[];
extern const char kHUPNewScoringVisitedCountUseDecayFactorParam[];

// Parameter names used by the HQP experimental scoring experiments.
extern const char kHQPExperimentalScoringBucketsParam[];
extern const char kHQPExperimentalScoringTopicalityThresholdParam[];

// Parameter names used by the experiment that limits the number of history
// urls indexed for suggestions.
extern const char kMaxNumHQPUrlsIndexedAtStartupOnLowEndDevicesParam[];
extern const char kMaxNumHQPUrlsIndexedAtStartupOnNonLowEndDevicesParam[];

// Parameter names used by num suggestion experiments.
extern const char kMaxZeroSuggestMatchesParam[];
extern const char kOmniboxMaxURLMatchesParam[];
extern const char kUIMaxAutocompleteMatchesByProviderParam[];
extern const char kUIMaxAutocompleteMatchesParam[];
// The URL cutoff and increased limit for dynamic max autocompletion.
// - When dynamic max autocompletion is disabled, the omnibox allows
//   UIMaxAutocompleteMatches suggestions.
// - When dynamic max autocompletion is enabled, the omnibox allows
//   suggestions up to the increased limit if doing so has URL cutoff or less
//   URL suggestions.
// E.g. a UIMaxAutocompleteMatches of 8, URL cutoff of 2, and increased limit of
// 10 translates to "show 10 or 9 suggestions if doing so includes at most 2
// URLs; otherwise show 8 suggestions.
extern const char kDynamicMaxAutocompleteUrlCutoffParam[];
extern const char kDynamicMaxAutocompleteIncreasedLimitParam[];

// Parameter names used by on device head model.
extern const char kOnDeviceHeadModelLocaleConstraint[];
extern const char kOnDeviceHeadModelSelectionFix[];

// The amount of time to wait before sending a new suggest request after the
// previous one unless overridden by a field trial parameter.
// Non-const because some unittests modify this value.
extern int kDefaultMinimumTimeBetweenSuggestQueriesMs;

// Parameter names used by omnibox experiments that hide the path (and
// optionally subdomains) in the steady state.
extern const char kOmniboxUIUnelideURLOnHoverThresholdMsParam[];

// Parameter names used by MIA experiments.
extern const char kSuppressPsuggestBackfillWithMIAParam[];

// `FeatureParam`s

// Local history zero-prefix (aka zero-suggest) and prefix suggestions.

// Whether to ignore all ZPS prefetch responses received from the Suggest
// service when the user is on a Google SRP. This can be used, for example,
// during experimentation to measure the performance impact of only the
// request/response portion of ZPS prefetching (i.e. without updating the
// user-visible list of suggestions in the Omnibox).
extern const base::FeatureParam<bool>
    kZeroSuggestPrefetchingOnSRPCounterfactual;

// Determines the debouncing delay (in milliseconds) to use when throttling ZPS
// prefetch requests.
extern const base::FeatureParam<int> kZeroSuggestPrefetchDebounceDelay;

// Determines whether to calculate debouncing delay relative to the latest
// successful run (instead of the latest run request).
extern const base::FeatureParam<bool> kZeroSuggestPrefetchDebounceFromLastRun;

// Determines the maximum number of entries stored by the in-memory ZPS cache.
extern const base::FeatureParam<int> kZeroSuggestCacheMaxSize;

// Returns true if any of the zero-suggest prefetching features are enabled.
bool IsZeroSuggestPrefetchingEnabled();

// Returns whether zero-suggest prefetching is enabled in the given context.
bool IsZeroSuggestPrefetchingEnabledInContext(
    metrics::OmniboxEventProto::PageClassification page_classification);

// Returns whether on-focus zero-suggest is enabled in the given context.
bool IsOnFocusZeroSuggestEnabledInContext(
    metrics::OmniboxEventProto::PageClassification page_classification);

// Returns whether suggestion group headers should be hidden in the Omnibox
// popup in the given context.
bool IsHideSuggestionGroupHeadersEnabledInContext(
    metrics::OmniboxEventProto::PageClassification page_classification);

// Rich autocompletion.
bool IsRichAutocompletionEnabled();
extern const base::FeatureParam<size_t>
    kRichAutocompletionAutocompleteTitlesMinChar;
extern const base::FeatureParam<size_t>
    kRichAutocompletionAutocompleteShortcutTextMinChar;

// Specifies the relevance scores for the Site Search Starter Pack ACMatches
// (e.g. @bookmarks, @history) provided by the Builtin Provider.
extern const base::FeatureParam<int> kSiteSearchStarterPackRelevanceScore;

// ---------------------------------------------------------
// ML Relevance Scoring ->

// The ML Relevance Scoring features and params configuration.
// Use `GetMLConfig()` to get the current configuration.
//
// `MLConfig` has the same thread-safety as base::FeatureList. The first call to
// `GetMLConfig()` (which performs initialization) must be done single threaded
// on the main thread. After that, it can be called from any thread.
struct MLConfig {
  MLConfig();
  ~MLConfig();
  MLConfig(const MLConfig&);
  MLConfig& operator=(const MLConfig& other);

  // If true, logs Omnibox URL scoring signals to OmniboxEventProto.
  // Equivalent to omnibox::kLogUrlScoringSignals.
  bool log_url_scoring_signals{false};

  // If true, enables history scoring signal annotator for populating history
  // scoring signals associated with Search suggestions. These signals will be
  // empty for Search suggestions otherwise.
  bool enable_history_scoring_signals_annotator_for_searches{false};

  // If true, enables scoring signal annotators for populating additional
  // Omnibox URL scoring signals for logging or ML scoring.
  bool enable_scoring_signals_annotators{false};

  // If true, document suggestions from the shortcut provider will include
  // shortcut signals.
  bool shortcut_document_signals{false};

  // If true, runs the ML scoring model to assign new relevance scores to the
  // URL suggestions and reranks them.
  // Equivalent to omnibox::kMlUrlScoring.
  bool ml_url_scoring{false};

  // If true, runs the ML scoring model but does not assign new relevance scores
  // to the URL suggestions and does not rerank them.
  // Equivalent to OmniboxFieldTrial::kMlUrlScoringCounterfactual.
  bool ml_url_scoring_counterfactual{false};

  // If true, increases the number of candidates the URL autocomplete providers
  // pass to the controller beyond `provider_max_matches`.
  // `ml_url_scoring_max_matches_by_provider` does nothing if this is true.
  // Equivalent to OmniboxFieldTrial::kMlUrlScoringUnlimitedNumCandidates.
  bool ml_url_scoring_unlimited_num_candidates{false};

  // If true, creates Omnibox autocomplete URL scoring model.
  // Equivalent to omnibox::kUrlScoringModel.
  bool url_scoring_model{false};

  // Sets the maximum matches provided by each provider.  See
  // `OmniboxFieldTrial::GetProviderMaxMatches()` for more info. When ML Scoring
  // is enabled, this param takes precedence over
  // `OmniboxFieldTrial::kUIMaxAutocompleteMatchesByProviderParam`. This param
  // has no effect if `ml_url_scoring_unlimited_num_candidates` is true.
  std::string ml_url_scoring_max_matches_by_provider;

  // There are 3 implementations for mapping ML scores [0, 1] to usable
  // relevances scores.
  // 1) The original implementation in `RunBatchUrlScoringModel()`. This
  //    redistributes the traditional relevance scores and shortcut boosting so
  //    that the highest ML scoring URLs are assigned the highest traditional
  //    scores, but the overall set of scores remains unchanged. This results in
  //    mostly stable search v URL balance, but can change the default match
  //    from a URL to a search; or vice versa; and therefore also change the
  //    number of URLs above searches by +/- 1; because it doesn't consider
  //    `allowed_to_be_default`. We've experimented with this for multiple
  //    milestone, so this has the advantage in potentially launching first.
  // 2) The `mapped_search_blending` implementation in
  //    `RunBatchUrlScoringModelMappedSearchBlending()`. It maps ML scores
  //    linearly to a relevance score. Unlike the above 2, instead of trying to
  //    maintain search v URL balance for each individual input, it tries to
  //    balance them across all inputs, but allows shifts for individual inputs.
  //    Not keeping the search v URL balance fixed for each individual input is
  //    the long term goal, though we may end up with a more complicated or ML
  //    approach.
  // 3) The `piecewise_mapped_search_blending` implementation in
  //    `RunBatchUrlScoringModelPiecewiseMappedSearchBlending()`. It maps ML
  //    scores to relevance scores using a piecewise function (which must be
  //    continuous with respect to ML scores) composed of individual line
  //    segments whose break points are specified by
  //    `piecewise_mapped_search_blending_break_points`. The Search vs Url
  //    behavior of this implementation is similar to that noted above in (2).

  // Enables approach (2) above.
  // Map ML scores [0, 1] to [`min`, `max`]. Groups URLs above searches if their
  // mapped relevance is greater than
  // `mapped_search_blending_grouping_threshold`.
  bool mapped_search_blending{false};
  int mapped_search_blending_min{600};
  int mapped_search_blending_max{2800};
  int mapped_search_blending_grouping_threshold{1400};

  // Enables approach (3) above.
  // Map ML scores [0, 1] to relevance scores by using a piecewise score mapping
  // function. Groups URLs above searches if their mapped relevance is greater
  // than `piecewise_mapped_search_blending_grouping_threshold`.
  bool piecewise_mapped_search_blending{false};
  int piecewise_mapped_search_blending_grouping_threshold{1400};
  // Specifies a list of N break points (x, y) which collectively define the N-1
  // line segments that comprise the piecewise score mapping function. The list
  // of break points must be sorted in ascending order with respect to their
  // x-coordinates. This list of break points will be applied to score any
  // suggestion which doesn't satisfy the criteria for applying one of the more
  // specific break points params listed below.
  // As an example, if we use "0,550;0.018,1300;0.14,1398;1,1422" as the value
  // for this param, then the resulting list of break points would be [(0, 550),
  // (0.018, 1300), (0.14, 1398), (1, 1422)].
  std::string piecewise_mapped_search_blending_break_points;
  // Similar to `piecewise_mapped_search_blending_break_points`, this param
  // specifies a list of break points that will only be used when scoring
  // verbatim URL suggestions.
  // A "verbatim URL" suggestion is any suggestion that is UWYT itself or has
  // been deduped with a UWYT suggestion.
  std::string piecewise_mapped_search_blending_break_points_verbatim_url;
  // Similar to `piecewise_mapped_search_blending_break_points`, this param
  // specifies a list of break points that will only be used when scoring
  // Search suggestions.
  std::string piecewise_mapped_search_blending_break_points_search;
  // Specifies a bias term that will be added to the relevance score which was
  // computed by the piecewise score mapping function. By varying this term,
  // it's possible to make the piecewise mapping function more or less
  // aggressive at a global scale.
  // The same bias param value will be used regardless of which one of the above
  // "break points" variants is currently in use.
  int piecewise_mapped_search_blending_relevance_bias{0};

  // If true, ML scoring service will utilize in-memory ML score cache.
  // Equivalent to omnibox::kMlUrlScoreCaching.
  bool ml_url_score_caching{false};
  // Maximum number of cached entries to store in the ML score cache.
  int max_ml_score_cache_size{30};

  // If true, Search suggestions will be eligible for re-ranking via ML scoring.
  bool enable_ml_scoring_for_searches{false};

  // If true, verbatim URL suggestions will be eligible for re-ranking via ML
  // scoring.
  bool enable_ml_scoring_for_verbatim_urls{false};
};

// A testing utility class for overriding the current configuration returned
// by the global or member `GetMLConfig()` and restoring it once the instance
// goes out of scope.
class ScopedMLConfigForTesting {
 public:
  ScopedMLConfigForTesting();
  ScopedMLConfigForTesting(const ScopedMLConfigForTesting&) = delete;
  ScopedMLConfigForTesting& operator=(const ScopedMLConfigForTesting&) = delete;
  ~ScopedMLConfigForTesting();

  // Returns the current configuration.
  MLConfig& GetMLConfig();

 private:
  std::unique_ptr<MLConfig> original_config_{nullptr};
};

// Returns the current configuration.
const MLConfig& GetMLConfig();

// If enabled, logs Omnibox scoring signals to OmniboxEventProto for training
// the ML scoring models.
bool IsReportingUrlScoringSignalsEnabled();

// If enabled, populates scoring signals of URL matches.
bool IsPopulatingUrlScoringSignalsEnabled();

// Whether the scoring signal annotators are enabled for logging Omnibox scoring
// signals to OmniboxEventProto.
bool AreScoringSignalsAnnotatorsEnabled();

// If enabled, runs the ML scoring model to assign new relevance scores to the
// URL suggestions and reranks them.
bool IsMlUrlScoringEnabled();

// If true, runs the ML scoring model but does not assign new relevance scores
// to URL suggestions.
bool IsMlUrlScoringCounterfactual();

// If true, increases the number of candidates the url autocomplete providers
// pass to the controller.
bool IsMlUrlScoringUnlimitedNumCandidatesEnabled();

// Whether the URL scoring model is enabled.
bool IsUrlScoringModelEnabled();

// Whether ML URL score caching is enabled.
bool IsMlUrlScoreCachingEnabled();

enum class PiecewiseMappingVariant {
  // Regular piecewise score mapping for most suggestion types.
  kRegular,
  // Piecewise score mapping specific to verbatim URL suggestions.
  kVerbatimUrl,
  // Piecewise score mapping specific to Search suggestions.
  kSearch,

  kPiecewiseMappingVariantSize,
};

// Converts the `piecewise_break_points` feature param into a vector of (x, y)
// coordinates specifying the "break points" of the piecewise ML score mapping
// function.
// The `mapping_variant` parameter allows callers to fetch an alternative list
// of break points which might be more relevant for suggestions of a certain
// type.
std::vector<std::pair<double, int>> GetPiecewiseMappingBreakPoints(
    PiecewiseMappingVariant mapping_variant =
        PiecewiseMappingVariant::kRegular);

// <- Ipad suggestions limit
// ---------------------------------------------------------
// <- ML Relevance Scoring
// ---------------------------------------------------------
// Actions In Suggest ->

constexpr base::FeatureParam<bool> kAnswerActionsCounterfactual(
    &omnibox::kOmniboxAnswerActions,
    "AnswerActionsCounterfactual",
    false);
constexpr base::FeatureParam<bool> kAnswerActionsShowAboveKeyboard(
    &omnibox::kOmniboxAnswerActions,
    "ShowAboveKeyboard",
    false);

constexpr base::FeatureParam<bool> kAnswerActionsShowIfUrlsPresent(
    &omnibox::kOmniboxAnswerActions,
    "ShowIfUrlsPresent",
    false);

constexpr base::FeatureParam<bool> kAnswerActionsShowRichCard(
    &omnibox::kOmniboxAnswerActions,
    "ShowRichCard",
    false);

// <- Actions In Suggest
// ---------------------------------------------------------
// Touch Down Trigger For Prefetch ->
extern const base::FeatureParam<int>
    kTouchDownTriggerForPrefetchMaxPrefetchesPerOmniboxSession;
// <- Touch Down Trigger For Prefetch
// ---------------------------------------------------------
// Site Search Starter Pack ->
// When non-empty, the value of this param overrides the `search_url` for the
// @gemini scope. This happens when the URL gets served, it does not affect the
// DB or TemplateURLService's copy of the URL.
extern const base::FeatureParam<std::string> kGeminiUrlOverride;

// Whether the expansion pack (the `StarterPackId::kGemini` keyword/engine) for
// the site search starter pack is enabled.
bool IsStarterPackExpansionEnabled();

// When true, enables an informational IPH message at the bottom of the Omnibox
// directing users to certain starter pack engines.
bool IsStarterPackIPHEnabled();

// <- Site Search Starter Pack
// ---------------------------------------------------------
// Power Tools -->
constexpr base::FeatureParam<size_t> kOmniboxNumNtpZpsRecentSearches{
    &omnibox::kNumNtpZpsRecentSearches, "omnibox_num_ntp_zps_recent_searches",
    15};
constexpr base::FeatureParam<size_t> kOmniboxNumNtpZpsTrendingSearches{
    &omnibox::kNumNtpZpsTrendingSearches,
    "omnibox_num_ntp_zps_trending_searches", 5};
constexpr base::FeatureParam<size_t> kOmniboxNumWebZpsRecentSearches{
    &omnibox::kNumWebZpsRecentSearches, "omnibox_num_web_zps_recent_searches",
    15};
constexpr base::FeatureParam<size_t> kOmniboxNumWebZpsRelatedSearches{
    &omnibox::kNumWebZpsRelatedSearches, "omnibox_num_web_zps_related_searches",
    8};
constexpr base::FeatureParam<size_t> kOmniboxNumWebZpsMostVisitedUrls{
    &omnibox::kNumWebZpsMostVisitedUrls,
    "omnibox_num_web_zps_most_visited_urls", 10};
constexpr base::FeatureParam<size_t> kOmniboxNumSrpZpsRecentSearches{
    &omnibox::kNumSrpZpsRecentSearches, "omnibox_num_srp_zps_recent_searches",
    15};
constexpr base::FeatureParam<size_t> kOmniboxNumSrpZpsRelatedSearches{
    &omnibox::kNumSrpZpsRelatedSearches, "omnibox_num_srp_zps_related_searches",
    15};
// <- Power Tools
// ---------------------------------------------------------
// Diagnostics -->
#if BUILDFLAG(IS_ANDROID)
inline constexpr base::FeatureParam<bool> kAndroidDiagInputConnection{
    &omnibox::kDiagnostics, "omnibox_diag_input_connection", false};
#endif
// <- Diagnostics
// ---------------------------------------------------------
// Mobile Parity update -->
inline constexpr base::FeatureParam<bool> kMobileParityRetrieveBuiltinFavicon{
    &omnibox::kOmniboxMobileParityUpdateV2, "retrieve_builtin_favicon", false};


inline constexpr base::FeatureParam<bool> kMobileParityEnableFeedForGoogleOnly{
    &omnibox::kOmniboxMobileParityUpdate, "enable_feed_for_google_only", true};
// <-- Mobile Parity update

// Aim shortcut for typed state ->

constexpr base::FeatureParam<int> kMinimumTypedCharactersToInvokeAimShortcut(
    &omnibox::kOmniboxAimShortcutTypedState,
    "MinimumTypedCharactersToInvokeAimShortcut",
    1);

// <- Aim shortcut for typed state

// New params should be inserted above this comment. They should be ordered
// consistently with `omnibox_features.h`. They should be formatted as:
// - Short comment categorizing the relevant features & params.
// - Optional: `bool Is[FeatureName]Enabled();` helpers that check if the
//   related features in `omnibox_features.h` are enabled.
// - Optional: Helper getter functions to determine the param values when
//   they're not trivial. E.g. a helper may be needed to return the min of 2
//   params. Trivial helpers that simply return the param values should be
//   omitted.
// - `extern const base::FeatureParam<[T]> k[ParamName];` declarations for
//   params. Param names should not begin with a `omnibox` prefix or end with a
//   `Param` suffix. Names for the same or related feature should share a common
//   prefix.
// An example:
/*
  // Drive suggestions.
  // True if the feature to enable the document provider is enabled.
  bool IsDocumentSuggestionsEnabled();
  // True if the feature to debounce the document provider is enabled.
  bool IsDocumentDebouncingEnabled();
  // The minimum input length for which to show document suggestions.
  extern const base::FeatureParam<int> kDocumentMinChar;
  // If true, document suggestions will be hidden but logged for analysis.
  extern const base::FeatureParam<bool> kDocumentCounterfactual;
*/

}  // namespace OmniboxFieldTrial

#endif  // COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_