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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.
#include "components/cronet/android/cronet_base_feature.h"
#include "base/debug/leak_annotations.h"
#include "base/feature_list.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/field_trial_params.h"
namespace cronet {
using ::org::chromium::net::httpflags::BaseFeatureOverrides;
void ApplyBaseFeatureOverrides(const BaseFeatureOverrides& overrides) {
if (base::FeatureList::GetInstance() != nullptr) {
LOG(WARNING) << "Not setting Cronet base::Feature overrides as "
"base::Feature is already initialized";
return;
}
// We need to ensure base::FieldTrialList is initialized, otherwise the call
// to base::FieldTrialList::CreateFieldTrial() below will crash.
{
// Intentional leak (singleton). Note that we can't use a static
// base::NoDestructor here because that would lead to the FieldTrialList
// singleton not getting properly reset between unit tests.
auto* const field_trial_list = new base::FieldTrialList();
ANNOTATE_LEAKING_OBJECT_PTR(field_trial_list);
(void)field_trial_list;
}
auto feature_list = std::make_unique<base::FeatureList>();
for (const auto& [feature_name, feature_state] : overrides.feature_states()) {
// Cronet uses its own bespoke metrics logging system, and never reports
// base::FieldTrial data back to Finch. We still need to provide a
// FieldTrial to be able to register the base::Feature override and to
// associate params, so let's create a fake one with bogus names. This is
// similar in principle to how Chrome base::Features can be overridden from
// the command line, and in fact the naming scheme below is inspired by how
// base::FeatureList::InitializeFromCommandLine() generates fake field trial
// and group names, with an additional "Cronet" prefix.
const std::string field_trial_name = "CronetStudy" + feature_name;
const std::string field_trial_group = "CronetGroup" + feature_name;
auto* const field_trial = base::FieldTrialList::CreateFieldTrial(
field_trial_name, field_trial_group);
CHECK(field_trial != nullptr)
<< "Unable to create field trial for feature: " << feature_name;
feature_list->RegisterFieldTrialOverride(
feature_name,
feature_state.has_enabled()
? (feature_state.enabled()
? base::FeatureList::OVERRIDE_ENABLE_FEATURE
: base::FeatureList::OVERRIDE_DISABLE_FEATURE)
: base::FeatureList::OVERRIDE_USE_DEFAULT,
field_trial);
if (!feature_state.params().empty()) {
base::AssociateFieldTrialParams(
field_trial_name, field_trial_group,
{feature_state.params().begin(), feature_state.params().end()});
}
}
base::FeatureList::SetInstance(std::move(feature_list));
}
} // namespace cronet
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