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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/chrome_browser_field_trials.h"
#include <optional>
#include <string>
#include "base/command_line.h"
#include "base/feature_list.h"
#include "base/files/file_util.h"
#include "base/metrics/field_trial.h"
#include "base/path_service.h"
#include "base/strings/string_util.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "chrome/browser/metrics/chrome_browser_sampling_trials.h"
#include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
#include "chrome/browser/metrics/chrome_metrics_service_client.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/chrome_switches.h"
#include "components/metrics/metrics_pref_names.h"
#include "components/metrics/persistent_histograms.h"
#include "components/version_info/version_info.h"
#if BUILDFLAG(IS_ANDROID)
#include "base/android/build_info.h"
#include "base/android/bundle_utils.h"
#include "base/task/thread_pool/environment_config.h"
#include "chrome/browser/android/flags/chrome_cached_flags.h"
#include "chrome/browser/flags/android/chrome_feature_list.h"
#include "chrome/common/chrome_features.h"
#endif
#if BUILDFLAG(IS_CHROMEOS)
#include "chrome/common/channel_info.h"
#include "chromeos/ash/services/multidevice_setup/public/cpp/first_run_field_trial.h"
#endif
#if BUILDFLAG(IS_LINUX)
#include "base/nix/xdg_util.h"
#include "ui/base/ui_base_features.h"
#endif // BUILDFLAG(IS_LINUX)
ChromeBrowserFieldTrials::ChromeBrowserFieldTrials(PrefService* local_state)
: local_state_(local_state) {
DCHECK(local_state_);
}
ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() = default;
void ChromeBrowserFieldTrials::SetUpClientSideFieldTrials(
bool has_seed,
const variations::EntropyProviders& entropy_providers,
base::FeatureList* feature_list) {
// Only create the fallback trials if there isn't already a variations seed
// being applied. This should occur during first run when first-run variations
// isn't supported. It's assumed that, if there is a seed, then it either
// contains the relevant studies, or is intentionally omitted, so no fallback
// is needed. The exception is for sampling trials. Fallback trials are
// created even if no variations seed was applied. This allows testing the
// fallback code by intentionally omitting the sampling trial from a
// variations seed.
metrics::CreateFallbackSamplingTrialsIfNeeded(
entropy_providers.default_entropy(), feature_list);
metrics::CreateFallbackUkmSamplingTrialIfNeeded(
entropy_providers.default_entropy(), feature_list);
#if BUILDFLAG(IS_CHROMEOS)
if (!has_seed) {
ash::multidevice_setup::CreateFirstRunFieldTrial(feature_list);
}
#endif
}
void ChromeBrowserFieldTrials::RegisterSyntheticTrials() {
#if BUILDFLAG(IS_ANDROID)
{
// BackgroundThreadPoolSynthetic field trial.
const char* group_name;
// Target group as indicated by finch feature.
bool feature_enabled =
base::FeatureList::IsEnabled(chrome::android::kBackgroundThreadPool);
// Whether the feature was overridden by either the commandline or Finch.
bool feature_overridden =
base::FeatureList::GetInstance()->IsFeatureOverridden(
chrome::android::kBackgroundThreadPool.name);
// Whether the feature was overridden manually via the commandline.
bool cmdline_overridden =
feature_overridden &&
base::FeatureList::GetInstance()->IsFeatureOverriddenFromCommandLine(
chrome::android::kBackgroundThreadPool.name);
// The finch feature value is cached by Java in a setting and applied via a
// command line flag. Check if this has happened -- it may not have happened
// if this is the first startup after the feature is enabled.
bool actually_enabled =
base::internal::CanUseBackgroundThreadTypeForWorkerThread();
// Use the default group if either the feature wasn't overridden or if the
// feature target state and actual state don't agree. Also separate users
// that override the feature via the commandline into separate groups.
if (actually_enabled != feature_enabled || !feature_overridden) {
group_name = "Default";
} else if (cmdline_overridden && feature_enabled) {
group_name = "ForceEnabled";
} else if (cmdline_overridden && !feature_enabled) {
group_name = "ForceDisabled";
} else if (feature_enabled) {
group_name = "Enabled";
} else {
group_name = "Disabled";
}
static constexpr char kBackgroundThreadPoolTrial[] =
"BackgroundThreadPoolSynthetic";
ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
kBackgroundThreadPoolTrial, group_name);
}
#endif // BUILDFLAG(IS_ANDROID)
}
#if BUILDFLAG(IS_LINUX)
// On Linux/Desktop platform variants, such as ozone/wayland, some features
// might need to be disabled as per OzonePlatform's runtime properties.
// OzonePlatform selection and initialization, in turn, depend on Chrome flags
// processing, namely 'ozone-platform-hint', so do it here.
//
// TODO(nickdiego): Move it back to ChromeMainDelegate::PostEarlyInitialization
// once ozone-platform-hint flag is dropped.
void ChromeBrowserFieldTrials::RegisterFeatureOverrides(
base::FeatureList* feature_list) {
std::unique_ptr<base::Environment> env = base::Environment::Create();
std::string xdg_session_type =
env->GetVar(base::nix::kXdgSessionTypeEnvVar).value_or(std::string());
if (xdg_session_type == "wayland") {
feature_list->RegisterExtraFeatureOverrides(
{{features::kEyeDropper, base::FeatureList::OVERRIDE_DISABLE_FEATURE}});
}
}
#endif // BUILDFLAG(IS_LINUX)
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