Move Field Trial Utils from chrome/common/variations to components/variations/field_trial_util

chrome/common/variations/variations_util.cc

-// Copyright 2014 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.
-
-#include "chrome/common/variations/variations_util.h"
-
-#include <stddef.h>
-
-#include <string>
-#include <vector>
-
-#include "base/command_line.h"
-#include "base/feature_list.h"
-#include "base/metrics/field_trial.h"
-#include "base/strings/string_split.h"
-#include "base/strings/stringprintf.h"
-#include "chrome/common/variations/fieldtrial_testing_config.h"
-#include "components/variations/variations_associated_data.h"
-#include "net/base/escape.h"
-
-namespace chrome_variations {
-
-namespace {
-
-std::string EscapeValue(const std::string& value) {
-  return net::UnescapeURLComponent(
-      value, net::UnescapeRule::PATH_SEPARATORS |
-                 net::UnescapeRule::URL_SPECIAL_CHARS_EXCEPT_PATH_SEPARATORS);
-}
-
-void AssociateParamsFromExperiment(
-    const std::string& study_name,
-    const FieldTrialTestingExperiment& experiment,
-    base::FeatureList* feature_list) {
-  if (experiment.params_size != 0) {
-    std::map<std::string, std::string> params;
-    for (size_t i = 0; i < experiment.params_size; ++i) {
-      const FieldTrialTestingExperimentParams& param = experiment.params[i];
-      params[param.key] = param.value;
-    }
-    variations::AssociateVariationParams(study_name, experiment.name, params);
-  }
-  base::FieldTrial* trial =
-      base::FieldTrialList::CreateFieldTrial(study_name, experiment.name);
-
-  if (!trial) {
-    DLOG(WARNING) << "Field trial config study skipped: " << study_name
-                  << "." << experiment.name
-                  << " (it is overridden from chrome://flags)";
-    return;
-  }
-
-  for (size_t i = 0; i < experiment.enable_features_size; ++i) {
-    feature_list->RegisterFieldTrialOverride(
-        experiment.enable_features[i],
-        base::FeatureList::OVERRIDE_ENABLE_FEATURE, trial);
-  }
-  for (size_t i = 0; i < experiment.disable_features_size; ++i) {
-    feature_list->RegisterFieldTrialOverride(
-        experiment.disable_features[i],
-        base::FeatureList::OVERRIDE_DISABLE_FEATURE, trial);
-  }
-}
-
-// Chooses an experiment taking into account the command line. Defaults to
-// picking the first experiment.
-const FieldTrialTestingExperiment& ChooseExperiment(
-    const FieldTrialTestingExperiment experiments[],
-    size_t experiment_size) {
-  DCHECK_GT(experiment_size, 0ul);
-  const auto& command_line = *base::CommandLine::ForCurrentProcess();
-  size_t chosen_index = 0;
-  for (size_t i = 1; i < experiment_size && chosen_index == 0; ++i) {
-    const auto& experiment = experiments[i];
-    if (experiment.forcing_flag &&
-        command_line.HasSwitch(experiment.forcing_flag)) {
-      chosen_index = i;
-      break;
-    }
-  }
-  DCHECK_GT(experiment_size, chosen_index);
-  return experiments[chosen_index];
-}
-
-} // namespace
-
-bool AssociateParamsFromString(const std::string& varations_string) {
-  // Format: Trial1.Group1:k1/v1/k2/v2,Trial2.Group2:k1/v1/k2/v2
-  std::set<std::pair<std::string, std::string>> trial_groups;
-  for (const base::StringPiece& experiment_group : base::SplitStringPiece(
-           varations_string, ",",
-           base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) {
-    std::vector<base::StringPiece> experiment = base::SplitStringPiece(
-        experiment_group, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
-    if (experiment.size() != 2) {
-      DLOG(ERROR) << "Experiment and params should be separated by ':'";
-      return false;
-    }
-
-    std::vector<std::string> group_parts = base::SplitString(
-        experiment[0], ".", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
-    if (group_parts.size() != 2) {
-      DLOG(ERROR) << "Trial and group name should be separated by '.'";
-      return false;
-    }
-
-    std::vector<std::string> key_values = base::SplitString(
-        experiment[1], "/", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
-    if (key_values.size() % 2 != 0) {
-      DLOG(ERROR) << "Param name and param value should be separated by '/'";
-      return false;
-    }
-    std::string trial = EscapeValue(group_parts[0]);
-    std::string group = EscapeValue(group_parts[1]);
-    auto trial_group = std::make_pair(trial, group);
-    if (trial_groups.find(trial_group) != trial_groups.end()) {
-      DLOG(ERROR) << base::StringPrintf(
-          "A (trial, group) pair listed more than once. (%s, %s)",
-          trial.c_str(), group.c_str());
-      return false;
-    }
-    trial_groups.insert(trial_group);
-    std::map<std::string, std::string> params;
-    for (size_t i = 0; i < key_values.size(); i += 2) {
-      std::string key = EscapeValue(key_values[i]);
-      std::string value = EscapeValue(key_values[i + 1]);
-      params[key] = value;
-    }
-    variations::AssociateVariationParams(trial, group, params);
-  }
-  return true;
-}
-
-void AssociateParamsFromFieldTrialConfig(const FieldTrialTestingConfig& config,
-                                         base::FeatureList* feature_list) {
-  for (size_t i = 0; i < config.studies_size; ++i) {
-    const FieldTrialTestingStudy& study = config.studies[i];
-    if (study.experiments_size > 0) {
-      AssociateParamsFromExperiment(
-          study.name,
-          ChooseExperiment(study.experiments, study.experiments_size),
-          feature_list);
-    } else {
-      DLOG(ERROR) << "Unexpected empty study: " << study.name;
-    }
-  }
-}
-
-void AssociateDefaultFieldTrialConfig(base::FeatureList* feature_list) {
-  AssociateParamsFromFieldTrialConfig(kFieldTrialConfig, feature_list);
-}
-
-}  // namespace chrome_variations