chrome/browser/performance_manager/metrics/metrics_provider_desktop.cc

// 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 "chrome/browser/performance_manager/metrics/metrics_provider_desktop.h"

#include "base/byte_count.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/numerics/safe_conversions.h"
#include "base/power_monitor/cpu_frequency_utils.h"
#include "base/process/process_metrics.h"
#include "base/system/sys_info.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/thread_pool.h"
#include "base/timer/timer.h"
#include "base/trace_event/trace_event.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/performance_manager/public/user_tuning/user_performance_tuning_manager.h"
#include "chrome/browser/profiles/profile_manager.h"
#include "components/performance_manager/public/user_tuning/prefs.h"
#include "components/prefs/pref_service.h"
#include "third_party/perfetto/include/perfetto/tracing/track.h"
#include "ui/accessibility/ax_mode.h"
#include "ui/accessibility/platform/ax_platform_node.h"

#if BUILDFLAG(IS_WIN)
#include "base/win/registry.h"
#endif

using performance_manager::user_tuning::prefs::kMemorySaverModeState;
using performance_manager::user_tuning::prefs::MemorySaverModeState;

namespace performance_manager {

namespace {

MetricsProviderDesktop* g_metrics_provider = nullptr;

#if SHOULD_COLLECT_CPU_FREQUENCY_METRICS()
enum class CpuThroughputEstimatedStatus {
  kNormal,
  kUnknown,
  kThrottled,
  kDescheduled,
  kMigrated,
};

CpuThroughputEstimatedStatus EstimateCpuThroughputStatus(
    bool migrated,
    std::optional<double> cpu_frequency_percent,
    std::optional<double> thread_time_percent,
    base::TimeDelta queued_time) {
  if (migrated) {
    // If the task migrated from one CPU to the other, report the status as
    // such. It's not relevant to check the thread time % in this instance,
    // since a migrated task has by definition been descheduled. Likewise,
    // checking the estimate vs nominal frequencies is also irrelevant, since
    // the frequency of the original and migrated cores might be different.
    return CpuThroughputEstimatedStatus::kMigrated;
  }

  if (!thread_time_percent) {
    return CpuThroughputEstimatedStatus::kUnknown;
  } else if (*thread_time_percent < 75.0) {
    // If the task is actually running for only 75% of its wall time or less, we
    // report it as having been descheduled
    return CpuThroughputEstimatedStatus::kDescheduled;
  }

  if (!cpu_frequency_percent) {
    return CpuThroughputEstimatedStatus::kUnknown;
  } else if (*cpu_frequency_percent < 75.0) {
    // If the task had a thread time close to its wall time, but we estimate its
    // CPU frequency as 75% of nominal or less, we report the CPU as being
    // throttled.
    return CpuThroughputEstimatedStatus::kThrottled;
  }

  return CpuThroughputEstimatedStatus::kNormal;
}

constexpr char kCpuEstimationEventCategory[] =
    "performance_manager.cpu_metrics";
constexpr char kCpuEstimationEvent[] = "CpuStatusSampling";

constexpr char kCpuEstimationStatusNormalEvent[] =
    "CpuStatusSampling.Status.Normal";
constexpr char kCpuEstimationStatusUnknownEvent[] =
    "CpuStatusSampling.Status.Unknown";
constexpr char kCpuEstimationStatusThrottledEvent[] =
    "CpuStatusSampling.Status.Throttled";
constexpr char kCpuEstimationStatusDescheduledEvent[] =
    "CpuStatusSampling.Status.Descheduled";
constexpr char kCpuEstimationStatusMigratedEvent[] =
    "CpuStatusSampling.Status.Migrated";

constexpr char kCpuEstimationQueuedEvent[] = "CpuStatusSampling.Queued";
constexpr char kCpuEstimationRunningEvent[] = "CpuStatusSampling.Running";
constexpr char kCpuEstimationThreadTimeEvent[] = "CpuStatusSampling.ThreadTime";
constexpr char kCpuEstimationDescheduledEvent[] =
    "CpuStatusSampling.Descheduled";

// This function emits trace events related to the status of the CPU throughput
// estimation task. In a trace, these events might look like this (where CSS is
// CpuStatusSampling):
//
// +-----------------------------------------------+
// |               CpuStatusSampling               |
// +-----------------------------------------------+
// |          CSS.Status.{estimated_status}        |
// +------------+----------------------------------+
// | CSS.Queued |          CSS.Running             |
// +------------+----------------+-----------------+
//              | CSS.ThreadTime | CSS.Descheduled |
//              +----------------+-----------------+
//
// CpuStatusSampling.Status.{estimated_status} will reflect what the estimation
// code thinks the status of the CPU is, between Normal, Unknown, Throttled,
// Descheduled, Migrated.
//
// CpuStatusSampling.Queued is the time between when the estimation task was
// posted and when it started running.
//
// CpuStatusSampling.Running is the time between when the task started running
// and when it finished
//
// CpuStatusSampling.ThreadTime is the CPU time of the running task
//
// CpuStatusSampling.Descheduled is the wall time the task spent off-cpu
void EmitCpuStatusSamplingTraceEvents(base::TimeTicks posted_at_time,
                                      base::TimeTicks started_running_time,
                                      base::TimeDelta thread_time,
                                      base::TimeDelta wall_time,
                                      CpuThroughputEstimatedStatus status) {
  void* id = g_metrics_provider;

  base::TimeTicks end_time = started_running_time + wall_time;

  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory, kCpuEstimationEvent,
                    perfetto::Track::FromPointer(id), posted_at_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  end_time);

  const char* selected;
  switch (status) {
    case CpuThroughputEstimatedStatus::kNormal:
      selected = kCpuEstimationStatusNormalEvent;
      break;

    case CpuThroughputEstimatedStatus::kUnknown:
      selected = kCpuEstimationStatusUnknownEvent;
      break;

    case CpuThroughputEstimatedStatus::kThrottled:
      selected = kCpuEstimationStatusThrottledEvent;
      break;

    case CpuThroughputEstimatedStatus::kDescheduled:
      selected = kCpuEstimationStatusDescheduledEvent;
      break;

    case CpuThroughputEstimatedStatus::kMigrated:
      selected = kCpuEstimationStatusMigratedEvent;
      break;
  }

  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory,
                    perfetto::StaticString(selected),
                    perfetto::Track::FromPointer(id), posted_at_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  end_time);

  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory, kCpuEstimationQueuedEvent,
                    perfetto::Track::FromPointer(id), posted_at_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  started_running_time);

  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory, kCpuEstimationRunningEvent,
                    perfetto::Track::FromPointer(id), started_running_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  end_time);

  // Emit a block for the running thread time
  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory, kCpuEstimationThreadTimeEvent,
                    perfetto::Track::FromPointer(id), started_running_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  started_running_time + thread_time);

  // And then one of the wall time spent descheduled
  TRACE_EVENT_BEGIN(kCpuEstimationEventCategory, kCpuEstimationDescheduledEvent,
                    perfetto::Track::FromPointer(id),
                    started_running_time + thread_time);
  TRACE_EVENT_END(kCpuEstimationEventCategory, perfetto::Track::FromPointer(id),
                  started_running_time + wall_time);
}
#endif  // SHOULD_COLLECT_CPU_FREQUENCY_METRICS()

#if BUILDFLAG(IS_WIN)
// Reports histograms describing the value of the HKEY_LOCAL_MACHINE ->
// Software\Microsoft\Windows NT\CurrentVersion\Image File ->
// FrontEndHeapDebugOptions registry key. We observed locally that the 0x10 bit
// activates stack collection on heap allocation, which results in unacceptable
// performance. We want to be sure that this isn't used widely in the field.
void RecordFrontEndHeapDebugOptionsHistogram() {
  // Outcome of reading the registry key. These values are persisted to logs.
  // Entries should not be renumbered and numeric values should never be reused.
  // LINT.IfChange(FrontEndHeapDebugOptionsOutcome)
  enum class FrontEndHeapDebugOptionsOutcome {
    kCannotOpenKey = 0,
    kCannotReadValue = 1,
    kSuccess = 2,
    kMaxValue = kSuccess,
  };
  // LINT.ThenChange(//tools/metrics/histograms/metadata/performance_manager/enums.xml:FrontEndHeapDebugOptionsOutcome)

  std::optional<FrontEndHeapDebugOptionsOutcome> outcome;
  base::win::RegKey key;
  if (key.Open(HKEY_LOCAL_MACHINE,
               L"Software\\Microsoft\\Windows NT\\CurrentVersion\\Image File "
               L"Execution Options\\chrome.exe",
               KEY_QUERY_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
    DWORD value = 0;
    if (key.ReadValueDW(L"FrontEndHeapDebugOptions", &value) == ERROR_SUCCESS) {
      base::UmaHistogramSparse(
          "PerformanceManager.RegistryStats.FrontEndHeapDebugOptionsValue",
          // Limit the number of distinct values recorded to this histogram, as
          // recommended by `base::UmaHistogramSparse()` documentation. The
          // highest bit observed being set in practice is 0x10 (for stack
          // collection on heap allocation). We set the maximum a little bit
          // above that, to be aware if higher bits are used in the field.
          std::clamp(base::saturated_cast<int>(value), 0, 0xff));
      outcome = FrontEndHeapDebugOptionsOutcome::kSuccess;
    } else {
      outcome = FrontEndHeapDebugOptionsOutcome::kCannotReadValue;
    }
  } else {
    outcome = FrontEndHeapDebugOptionsOutcome::kCannotOpenKey;
  }

  CHECK(outcome.has_value());
  base::UmaHistogramEnumeration(
      "PerformanceManager.RegistryStats.FrontEndHeapDebugOptionsOutcome",
      outcome.value());
}
#endif  // BUILDFLAG(IS_WIN)

}  // namespace

// Tracks the proportion of time a specific mode was enabled during this
// object's entire lifetime, and records it to a specified histogram on
// destruction.
class ScopedTimeInModeTracker {
 public:
  ScopedTimeInModeTracker(bool enabled, const std::string& histogram_name)
      : currently_enabled_(enabled),
        current_interval_start_(base::LiveTicks::Now()),
        start_(current_interval_start_),
        histogram_name_(histogram_name) {}

  ~ScopedTimeInModeTracker() {
    // Ensure `time_spent_enabled_` is updated if the mode was currently
    // enabled. This doesn't call `ModeChanged` directly to ensure the value of
    // `now` used for the total time computation is the same as was used to
    // close the interval.
    base::LiveTicks now = base::LiveTicks::Now();

    CHECK(current_interval_start_ <= now);
    CHECK(start_ <= now);

    if (currently_enabled_) {
      time_spent_enabled_ += now - current_interval_start_;
    }

    base::TimeDelta total_time = now - start_;

    // Time spent enabled should be lower or equal to the total time this was
    // active.
    CHECK_LE(time_spent_enabled_, total_time);
    // Check that the `time_spent_enabled_ * 100` operation can't overflow.
    CHECK_LE(time_spent_enabled_.InMicroseconds(),
             std::numeric_limits<int64_t>::max() / 100);

    // `total_time` being 0 would mean the object was constructed and destructed
    // without the clock advancing a single microsecond. This shouldn't happen
    // in production but can happen in tests that use mock time. Treat this as
    // an interval that has only been in the current state.
    unsigned int percent_enabled = currently_enabled_ ? 100 : 0;
    if (total_time.is_positive()) {
      // Do the computation in microseconds to avoid prior truncation since it's
      // `TimeDelta`'s internal representation.
      int64_t checked_percent =
          (base::CheckMul(time_spent_enabled_.InMicroseconds(), 100) /
           total_time.InMicroseconds())
              .ValueOrDie();

      CHECK(base::IsValueInRangeForNumericType<unsigned int>(checked_percent));

      percent_enabled = checked_percent;
    }

    CHECK_LE(percent_enabled, 100U);

    base::UmaHistogramPercentage(histogram_name_, percent_enabled);
  }

  void ModeChanged(bool enabled) {
    if (currently_enabled_ == enabled) {
      // It's possible for the pref to be notified as "changed" even if it's
      // "changing" to the same state it's already in when going to/from
      // "enabled with heuristic mode" to/from "enabled on timer mode".
      return;
    }

    base::LiveTicks now = base::LiveTicks::Now();

    CHECK(current_interval_start_ <= now);

    if (currently_enabled_) {
      time_spent_enabled_ += now - current_interval_start_;
    }

    currently_enabled_ = enabled;
    current_interval_start_ = now;
  }

 private:
  bool currently_enabled_;

  base::TimeDelta time_spent_enabled_;
  base::LiveTicks current_interval_start_;
  base::LiveTicks start_;

  std::string histogram_name_;
};

// static
MetricsProviderDesktop* MetricsProviderDesktop::GetInstance() {
  DCHECK(g_metrics_provider);
  return g_metrics_provider;
}

MetricsProviderDesktop::~MetricsProviderDesktop() {
  DCHECK_EQ(this, g_metrics_provider);
  g_metrics_provider = nullptr;
}

void MetricsProviderDesktop::Initialize() {
  DCHECK(!initialized_);

  pref_change_registrar_.Init(local_state_);
  pref_change_registrar_.Add(
      kMemorySaverModeState,
      base::BindRepeating(&MetricsProviderDesktop::OnMemorySaverPrefChanged,
                          base::Unretained(this)));
  performance_manager::user_tuning::BatterySaverModeManager::GetInstance()
      ->AddObserver(this);
  battery_saver_enabled_ =
      performance_manager::user_tuning::BatterySaverModeManager::GetInstance()
          ->IsBatterySaverActive();

  initialized_ = true;
  current_mode_ = ComputeCurrentMode();

  ResetTrackers();

  PostDiskMetricsTask();
}

void MetricsProviderDesktop::ProvideCurrentSessionData(
    metrics::ChromeUserMetricsExtension* uma_proto) {
  // It's valid for this to be called when `initialized_` is false if the finch
  // features controlling battery saver and memory saver are disabled.
  // TODO(crbug.com/40233418): CHECK(initialized_) when the features are enabled
  // and removed.
  base::UmaHistogramEnumeration("PerformanceManager.UserTuning.EfficiencyMode",
                                current_mode_);

  // Resetting the trackers will cause the existing ones to record their
  // histogram.
  ResetTrackers();

  // Set `current_mode_` to represent the state of the modes as they are now, so
  // that this mode is what is adequately reported at the next report, unless it
  // changes in the meantime.
  current_mode_ = ComputeCurrentMode();

  RecordDiskMetrics();

#if BUILDFLAG(IS_WIN)
  RecordFrontEndHeapDebugOptionsHistogram();
#endif  // BUILDFLAG(IS_WIN)

  // Request a disk measurement so it's ready for the next interval
  PostDiskMetricsTask();
}

MetricsProviderDesktop::MetricsProviderDesktop(PrefService* local_state)
    : local_state_(local_state),
      disk_metrics_getter_(
          base::ThreadPool::CreateSequencedTaskRunner({base::MayBlock()})) {
  DCHECK(!g_metrics_provider);
  g_metrics_provider = this;

#if SHOULD_COLLECT_CPU_FREQUENCY_METRICS()
  ScheduleCpuFrequencyTask();
#endif  // SHOULD_COLLECT_CPU_FREQUENCY_METRICS()
}

void MetricsProviderDesktop::OnBatterySaverActiveChanged(bool is_active) {
  battery_saver_enabled_ = is_active;
  battery_saver_mode_tracker_->ModeChanged(battery_saver_enabled_);
  OnTuningModesChanged();
}

void MetricsProviderDesktop::OnMemorySaverPrefChanged() {
  memory_saver_mode_tracker_->ModeChanged(IsMemorySaverEnabled());
  OnTuningModesChanged();
}

void MetricsProviderDesktop::OnTuningModesChanged() {
  EfficiencyMode new_mode = ComputeCurrentMode();

  // If the mode changes between UMA reports, mark it as Mixed for this
  // interval.
  if (current_mode_ != new_mode) {
    current_mode_ = EfficiencyMode::kMixed;
  }
}

MetricsProviderDesktop::EfficiencyMode
MetricsProviderDesktop::ComputeCurrentMode() const {
  // It's valid for this to be uninitialized if the battery saver/high
  // efficiency modes are unavailable. In that case, the browser is running in
  // normal mode, so return kNormal.
  // TODO(crbug.com/40233418): Change this to a DCHECK when the features are
  // enabled and removed.
  if (!initialized_) {
    return EfficiencyMode::kNormal;
  }

  // It's possible for this function to be called during shutdown, after
  // BatterySaverModeManager is destroyed. Do not access UPTM directly from
  // here.

  bool high_efficiency_enabled = IsMemorySaverEnabled();

  if (high_efficiency_enabled && battery_saver_enabled_) {
    return EfficiencyMode::kBoth;
  }

  if (high_efficiency_enabled) {
    return EfficiencyMode::kMemorySaver;
  }

  if (battery_saver_enabled_) {
    return EfficiencyMode::kBatterySaver;
  }

  return EfficiencyMode::kNormal;
}

bool MetricsProviderDesktop::IsMemorySaverEnabled() const {
  return local_state_->GetInteger(kMemorySaverModeState) !=
         static_cast<int>(MemorySaverModeState::kDisabled);
}

void MetricsProviderDesktop::ResetTrackers() {
  battery_saver_mode_tracker_ = std::make_unique<ScopedTimeInModeTracker>(
      battery_saver_enabled_,
      "PerformanceManager.UserTuning.BatterySaverModeEnabledPercent");
  memory_saver_mode_tracker_ = std::make_unique<ScopedTimeInModeTracker>(
      IsMemorySaverEnabled(),
      "PerformanceManager.UserTuning.MemorySaverModeEnabledPercent");
}

#if SHOULD_COLLECT_CPU_FREQUENCY_METRICS()
// static
void MetricsProviderDesktop::RecordCpuFrequencyMetrics(
    base::TimeTicks posted_at_time) {
  auto started_running_time = base::TimeTicks::Now();
  auto queued_time = started_running_time - posted_at_time;

  static const double kHzInMhz = 1000 * 1000;

  std::optional<base::CpuThroughputEstimationResult> cpu_throughput =
      base::EstimateCpuThroughput();
  base::CpuFrequencyInfo cpu_frequency_info = base::GetCpuFrequencyInfo();

  if (!cpu_throughput) {
    return;
  }

  std::string_view core_type_suffix = "Performance";
  if (cpu_frequency_info.type == base::CpuFrequencyInfo::CoreType::kBalanced) {
    core_type_suffix = "Balanced";
  } else if (cpu_frequency_info.type ==
             base::CpuFrequencyInfo::CoreType::kEfficiency) {
    core_type_suffix = "Efficiency";
  }

  base::UmaHistogramCustomMicrosecondsTimes(
      base::StrCat(
          {"CPU.Experimental.CpuEstimationTaskQueuedTime.", core_type_suffix}),
      queued_time, base::Microseconds(1), base::Seconds(1), 50);

  base::UmaHistogramCustomMicrosecondsTimes(
      base::StrCat(
          {"CPU.Experimental.CpuEstimationTaskTotalTime.", core_type_suffix}),
      queued_time + cpu_throughput->wall_time, base::Microseconds(1),
      base::Seconds(1), 50);

  base::UmaHistogramCustomMicrosecondsTimes(
      base::StrCat(
          {"CPU.Experimental.CpuEstimationTaskThreadTime.", core_type_suffix}),
      cpu_throughput->thread_time, base::Microseconds(1), base::Seconds(1), 50);

  base::UmaHistogramCustomMicrosecondsTimes(
      base::StrCat(
          {"CPU.Experimental.CpuEstimationTaskWallTime.", core_type_suffix}),
      cpu_throughput->wall_time, base::Microseconds(1), base::Seconds(1), 50);

  base::UmaHistogramBoolean("CPU.Experimental.CpuEstimationTaskMigrated",
                            cpu_throughput->migrated);

  std::optional<double> cpu_frequency_percent = std::nullopt;
  if (!cpu_throughput->migrated) {
    // Don't record frequency metrics if the code migrated from one CPU to
    // another in the middle of the estimation loop. This is because the nominal
    // frequency of the start and end cores might be different.

    double estimated_mhz = cpu_throughput->estimated_frequency / kHzInMhz;

    // Max/Limit can (rarely) be 0 in the field, perhaps in virtualized or
    // sandboxed environments.
    if (cpu_frequency_info.max_mhz > 0UL) {
      cpu_frequency_percent = estimated_mhz * 100.0 /
                              static_cast<double>(cpu_frequency_info.max_mhz);

      base::UmaHistogramPercentage(
          base::StrCat({"CPU.Experimental.EstimatedFrequencyAsPercentOfMax.",
                        core_type_suffix}),
          static_cast<int>(*cpu_frequency_percent));
    }

    if (cpu_frequency_info.mhz_limit > 0UL) {
      base::UmaHistogramPercentage(
          base::StrCat({"CPU.Experimental.EstimatedFrequencyAsPercentOfLimit.",
                        core_type_suffix}),
          static_cast<int>(estimated_mhz * 100.0 /
                           static_cast<double>(cpu_frequency_info.mhz_limit)));
    }
  }

  // These can be 0 in tests
  if (!cpu_throughput->thread_time.is_zero() &&
      !cpu_throughput->wall_time.is_zero()) {
    std::optional<double> thread_time_percent =
        cpu_throughput->thread_time / cpu_throughput->wall_time * 100.0;
    base::UmaHistogramPercentage(
        base::StrCat({"CPU.Experimental.CpuEstimationThreadTimePercent.",
                      core_type_suffix}),
        static_cast<int>(*thread_time_percent));

    CpuThroughputEstimatedStatus status = EstimateCpuThroughputStatus(
        cpu_throughput->migrated, cpu_frequency_percent, thread_time_percent,
        queued_time);
    EmitCpuStatusSamplingTraceEvents(posted_at_time, started_running_time,
                                     cpu_throughput->thread_time,
                                     cpu_throughput->wall_time, status);
  }

  ScheduleCpuFrequencyTask();
}

// static
void MetricsProviderDesktop::ScheduleCpuFrequencyTask() {
  static constexpr base::TimeDelta kCpuThroughputSamplingInterval =
      base::Minutes(5);
  base::ThreadPool::PostDelayedTask(
      FROM_HERE,
      {base::TaskPriority::USER_VISIBLE,
       base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
      base::BindOnce(&MetricsProviderDesktop::PostCpuFrequencyEstimation),
      kCpuThroughputSamplingInterval);
}

// static
void MetricsProviderDesktop::PostCpuFrequencyEstimation() {
  base::ThreadPool::PostTask(
      FROM_HERE,
      {base::TaskPriority::USER_VISIBLE,
       base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
      base::BindOnce(&MetricsProviderDesktop::RecordCpuFrequencyMetrics,
                     base::TimeTicks::Now()));
}
#endif  // SHOULD_COLLECT_CPU_FREQUENCY_METRICS()

void MetricsProviderDesktop::RecordDiskMetrics() {
  if (!pending_disk_metrics_) {
    // The measurements aren't ready yet, don't report anything.
    return;
  }

  if (pending_disk_metrics_->free_bytes.is_negative() ||
      pending_disk_metrics_->total_bytes.is_negative()) {
    return;
  }

  base::UmaHistogramCustomCounts(
      "PerformanceManager.DiskStats.UserDataDirFreeSpaceMb",
      pending_disk_metrics_->free_bytes.InMiB(), 0,
      base::GiB(10)
          .InMiB(),  // It's fine to bucket everything >10Gb as "large enough"
      100);
  // Also report as a percentage of capacity
  base::UmaHistogramPercentage(
      "PerformanceManager.DiskStats.UserDataDirFreeSpacePercent",
      pending_disk_metrics_->free_bytes.InBytes() * 100 /
          pending_disk_metrics_->total_bytes.InBytes());

  pending_disk_metrics_ = std::nullopt;
}

void MetricsProviderDesktop::PostDiskMetricsTask() {
  if (!g_browser_process || !g_browser_process->profile_manager()) {
    // It's possible to have a null browser process or a null profile manager in
    // unit tests.
    return;
  }

  // Records the free/available space on the disk that hosts the user data dir.
  ProfileManager* profile_manager = g_browser_process->profile_manager();
  const base::FilePath& user_data_dir = profile_manager->user_data_dir();

  disk_metrics_getter_
      .AsyncCall(&MetricsProviderDesktop::DiskMetricsThreadPoolGetter::
                     ComputeDiskMetrics)
      .WithArgs(user_data_dir)
      .Then(base::BindOnce(&MetricsProviderDesktop::SavePendingDiskMetrics,
                           base::Unretained(this)));
}

MetricsProviderDesktop::DiskMetrics
MetricsProviderDesktop::DiskMetricsThreadPoolGetter::ComputeDiskMetrics(
    const base::FilePath& user_data_dir) {
  return {
      .free_bytes =
          base::ByteCount(base::SysInfo::AmountOfFreeDiskSpace(user_data_dir)),
      .total_bytes =
          base::ByteCount(base::SysInfo::AmountOfTotalDiskSpace(user_data_dir)),
  };
}

void MetricsProviderDesktop::SavePendingDiskMetrics(DiskMetrics metrics) {
  pending_disk_metrics_ = metrics;
}

}  // namespace performance_manager