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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/features.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/variations/feature_overrides.h"
#include "components/version_info/version_info.h"
#if BUILDFLAG(IS_ANDROID)
#include "base/android/background_thread_pool_field_trial.h"
#include "base/android/build_info.h"
#include "base/android/bundle_utils.h"
#include "base/task/thread_pool/environment_config.h"
#include "build/android_buildflags.h"
#include "chrome/browser/android/flags/chrome_cached_flags.h"
#include "chrome/browser/flags/android/chrome_feature_list.h"
#include "chrome/browser/media/webrtc/desktop_media_picker.h"
#include "chrome/common/chrome_features.h"
#include "content/public/common/content_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)
{
auto trial_info =
base::android::BackgroundThreadPoolFieldTrial::GetTrialInfo();
if (trial_info.has_value()) {
// The annotation mode is set to |kCurrentLog| since the field trial has
// taken effect at process startup.
ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
trial_info->trial_name, trial_info->group_name,
variations::SyntheticTrialAnnotationMode::kCurrentLog);
}
}
#endif // BUILDFLAG(IS_ANDROID)
}
void ChromeBrowserFieldTrials::RegisterFeatureOverrides(
base::FeatureList* feature_list) {
variations::FeatureOverrides feature_overrides(*feature_list);
#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.
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_overrides.DisableFeature(features::kEyeDropper);
}
#elif BUILDFLAG(IS_ANDROID) // BUILDFLAG(IS_LINUX)
#if BUILDFLAG(IS_DESKTOP_ANDROID)
// Nota bene: Anything here is expected to be short-lived, unless deemed too
// risky to launch to non-desktop platforms. New features being added here
// should be the exception, and not the norm. Instead, you should place the
// override in the generic IS_ANDROID block below, guarded by an appropriate
// runtime check.
// If enabled, render processes associated only with tabs in unfocused windows
// will be downgraded to "vis" priority, rather than remaining at "fg". This
// will allow tabs in unfocused windows to be prioritized for OOM kill in
// low-memory scenarios.
feature_overrides.EnableFeature(chrome::android::kChangeUnfocusedPriority);
// Enable by default for desktop platforms, pending a tablet rollout using the
// same flag.
// TODO(crbug.com/368058472): Remove when tablet rollout is complete.
feature_overrides.EnableFeature(chrome::android::kDisableInstanceLimit);
// Enables media capture (tab+window+screen sharing).
// TODO(crbug.com/352187279): Remove when tablet rollout is complete.
feature_overrides.EnableFeature(kAndroidMediaPicker);
feature_overrides.EnableFeature(features::kUserMediaScreenCapturing);
// Enable desktop tab management features.
// TODO(crbug.com/422902880): Remove when tablet rollout is complete.
feature_overrides.EnableFeature(
base::features::kUseSharedRebindServiceConnection);
// TODO(crbug.com/422902940): Remove when tablet rollout is complete.
feature_overrides.EnableFeature(
base::features::kBackgroundNotPerceptibleBinding);
// TODO(crbug.com/422902625): Remove when rollout is complete to all form
// factors.
feature_overrides.EnableFeature(chrome::android::kProcessRankPolicyAndroid);
feature_overrides.EnableFeature(features::kGroupRebindingForGroupImportance);
feature_overrides.EnableFeature(chrome::android::kProtectedTabsAndroid);
// TODO(crbug.com/422903297): Remove when tablet rollout is complete.
feature_overrides.EnableFeature(features::kRendererProcessLimitOnAndroid);
#endif // BUILDFLAG(IS_DESKTOP_ANDROID)
// Desktop-first features which are past incubation should either end up here,
// or to a finch trial that enables it for all form factors.
#endif // BUILDFLAG(IS_ANDROID)
}
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