chrome/browser/chromeos/system/automatic_reboot_manager.cc - platform/external/chromium_org - Git at Google

 // Copyright (c) 2013 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/browser/chromeos/system/automatic_reboot_manager.h"

 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>

 #include <algorithm>
 #include <string>

 #include "ash/shell.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/path_service.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time/tick_clock.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/system/automatic_reboot_manager_observer.h"
 #include "chrome/common/pref_names.h"
 #include "chromeos/chromeos_paths.h"
 #include "chromeos/chromeos_switches.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "components/user_manager/user_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "ui/wm/core/user_activity_detector.h"

 namespace chromeos {
 namespace system {

 namespace {

 const int kMinRebootUptimeMs = 60 * 60 * 1000;     // 1 hour.
 const int kLoginManagerIdleTimeoutMs = 60 * 1000;  // 60 seconds.
 const int kGracePeriodMs = 24 * 60 * 60 * 1000;    // 24 hours.
 const int kOneKilobyte = 1 << 10;                  // 1 kB in bytes.

 base::TimeDelta ReadTimeDeltaFromFile(const base::FilePath& path) {
   base::ThreadRestrictions::AssertIOAllowed();
   base::ScopedFD fd(
       HANDLE_EINTR(open(path.value().c_str(), O_RDONLY | O_NOFOLLOW)));
   if (!fd.is_valid())
     return base::TimeDelta();

   std::string contents;
   char buffer[kOneKilobyte];
   ssize_t length;
   while ((length = HANDLE_EINTR(read(fd.get(), buffer, sizeof(buffer)))) > 0)
     contents.append(buffer, length);

   double seconds;
   if (!base::StringToDouble(contents.substr(0, contents.find(' ')), &seconds) ||
       seconds < 0.0) {
     return base::TimeDelta();
   }
   return base::TimeDelta::FromMilliseconds(seconds * 1000.0);
 }

 void GetSystemEventTimes(
     scoped_refptr<base::SingleThreadTaskRunner> reply_task_runner,
     base::Callback<void(
         const AutomaticRebootManager::SystemEventTimes&)> reply) {
   base::FilePath uptime_file;
   CHECK(PathService::Get(chromeos::FILE_UPTIME, &uptime_file));
   base::FilePath update_reboot_needed_uptime_file;
   CHECK(PathService::Get(chromeos::FILE_UPDATE_REBOOT_NEEDED_UPTIME,
                          &update_reboot_needed_uptime_file));
   reply_task_runner->PostTask(FROM_HERE, base::Bind(reply,
       AutomaticRebootManager::SystemEventTimes(
           ReadTimeDeltaFromFile(uptime_file),
           ReadTimeDeltaFromFile(update_reboot_needed_uptime_file))));
 }

 void SaveUpdateRebootNeededUptime() {
   base::ThreadRestrictions::AssertIOAllowed();
   const base::TimeDelta kZeroTimeDelta;

   base::FilePath update_reboot_needed_uptime_file;
   CHECK(PathService::Get(chromeos::FILE_UPDATE_REBOOT_NEEDED_UPTIME,
                          &update_reboot_needed_uptime_file));
   const base::TimeDelta last_update_reboot_needed_uptime =
       ReadTimeDeltaFromFile(update_reboot_needed_uptime_file);
   if (last_update_reboot_needed_uptime != kZeroTimeDelta)
     return;

   base::FilePath uptime_file;
   CHECK(PathService::Get(chromeos::FILE_UPTIME, &uptime_file));
   const base::TimeDelta uptime = ReadTimeDeltaFromFile(uptime_file);
   if (uptime == kZeroTimeDelta)
     return;

   base::ScopedFD fd(HANDLE_EINTR(
       open(update_reboot_needed_uptime_file.value().c_str(),
            O_CREAT | O_WRONLY | O_TRUNC | O_NOFOLLOW,
            0666)));
   if (!fd.is_valid())
     return;

   std::string update_reboot_needed_uptime =
       base::DoubleToString(uptime.InSecondsF());
   base::WriteFileDescriptor(fd.get(), update_reboot_needed_uptime.c_str(),
                             update_reboot_needed_uptime.size());
 }

 }  // namespace

 AutomaticRebootManager::SystemEventTimes::SystemEventTimes()
     : has_boot_time(false),
       has_update_reboot_needed_time(false) {
 }

 AutomaticRebootManager::SystemEventTimes::SystemEventTimes(
     const base::TimeDelta& uptime,
     const base::TimeDelta& update_reboot_needed_uptime)
     : has_boot_time(false),
       has_update_reboot_needed_time(false) {
   const base::TimeDelta kZeroTimeDelta;
   if (uptime == kZeroTimeDelta)
     return;
   boot_time = base::TimeTicks::Now() - uptime;
   has_boot_time = true;
   if (update_reboot_needed_uptime == kZeroTimeDelta)
     return;
   // Calculate the time at which an update was applied and a reboot became
   // necessary in base::TimeTicks::Now() ticks.
   update_reboot_needed_time = boot_time + update_reboot_needed_uptime;
   has_update_reboot_needed_time = true;
 }

 AutomaticRebootManager::AutomaticRebootManager(
     scoped_ptr<base::TickClock> clock)
     : clock_(clock.Pass()),
       have_boot_time_(false),
       have_update_reboot_needed_time_(false),
       reboot_requested_(false),
       weak_ptr_factory_(this) {
   local_state_registrar_.Init(g_browser_process->local_state());
   local_state_registrar_.Add(prefs::kUptimeLimit,
                              base::Bind(&AutomaticRebootManager::Reschedule,
                                         base::Unretained(this)));
   local_state_registrar_.Add(prefs::kRebootAfterUpdate,
                              base::Bind(&AutomaticRebootManager::Reschedule,
                                         base::Unretained(this)));
   notification_registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
       content::NotificationService::AllSources());

   DBusThreadManager* dbus_thread_manager = DBusThreadManager::Get();
   dbus_thread_manager->GetPowerManagerClient()->AddObserver(this);
   dbus_thread_manager->GetUpdateEngineClient()->AddObserver(this);

   // If no user is logged in, a reboot may be performed whenever the user is
   // idle. Start listening for user activity to determine whether the user is
   // idle or not.
   if (!user_manager::UserManager::Get()->IsUserLoggedIn()) {
     if (ash::Shell::HasInstance())
       ash::Shell::GetInstance()->user_activity_detector()->AddObserver(this);
     notification_registrar_.Add(this, chrome::NOTIFICATION_LOGIN_USER_CHANGED,
         content::NotificationService::AllSources());
     login_screen_idle_timer_.reset(
         new base::OneShotTimer<AutomaticRebootManager>);
     OnUserActivity(NULL);
   }

   // In a regular browser, base::ThreadTaskRunnerHandle::Get() and
   // base::MessageLoopProxy::current() return pointers to the same object.
   // In unit tests, using base::ThreadTaskRunnerHandle::Get() has the advantage
   // that it allows a custom base::SingleThreadTaskRunner to be injected.
   content::BrowserThread::GetBlockingPool()->PostWorkerTaskWithShutdownBehavior(
       FROM_HERE,
       base::Bind(&GetSystemEventTimes,
                  base::ThreadTaskRunnerHandle::Get(),
                  base::Bind(&AutomaticRebootManager::Init,
                             weak_ptr_factory_.GetWeakPtr())),
       base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
 }

 AutomaticRebootManager::~AutomaticRebootManager() {
   FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
                     observers_,
                     WillDestroyAutomaticRebootManager());

   DBusThreadManager* dbus_thread_manager = DBusThreadManager::Get();
   dbus_thread_manager->GetPowerManagerClient()->RemoveObserver(this);
   dbus_thread_manager->GetUpdateEngineClient()->RemoveObserver(this);
   if (ash::Shell::HasInstance())
     ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
 }

 void AutomaticRebootManager::AddObserver(
     AutomaticRebootManagerObserver* observer) {
   observers_.AddObserver(observer);
 }

 void AutomaticRebootManager::RemoveObserver(
     AutomaticRebootManagerObserver* observer) {
   observers_.RemoveObserver(observer);
 }

 void AutomaticRebootManager::SuspendDone(
     const base::TimeDelta& sleep_duration) {
   MaybeReboot(true);
 }

 void AutomaticRebootManager::UpdateStatusChanged(
     const UpdateEngineClient::Status& status) {
   // Ignore repeated notifications that a reboot is necessary. This is important
   // so that only the time of the first notification is taken into account and
   // repeated notifications do not postpone the reboot request and grace period.
   if (status.status != UpdateEngineClient::UPDATE_STATUS_UPDATED_NEED_REBOOT ||
       !have_boot_time_ || have_update_reboot_needed_time_) {
     return;
   }

   content::BrowserThread::PostBlockingPoolTask(
       FROM_HERE, base::Bind(&SaveUpdateRebootNeededUptime));

   update_reboot_needed_time_ = clock_->NowTicks();
   have_update_reboot_needed_time_ = true;

   Reschedule();
 }

 void AutomaticRebootManager::OnUserActivity(const ui::Event* event) {
   if (!login_screen_idle_timer_)
     return;

   // Destroying and re-creating the timer ensures that Start() posts a fresh
   // task with a delay of exactly |kLoginManagerIdleTimeoutMs|, ensuring that
   // the timer fires predictably in tests.
   login_screen_idle_timer_.reset(
       new base::OneShotTimer<AutomaticRebootManager>);
   login_screen_idle_timer_->Start(
       FROM_HERE,
       base::TimeDelta::FromMilliseconds(kLoginManagerIdleTimeoutMs),
       base::Bind(&AutomaticRebootManager::MaybeReboot,
                  base::Unretained(this),
                  false));
 }

 void AutomaticRebootManager::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   if (type == chrome::NOTIFICATION_APP_TERMINATING) {
     if (user_manager::UserManager::Get()->IsUserLoggedIn()) {
       // The browser is terminating during a session, either because the session
       // is ending or because the browser is being restarted.
       MaybeReboot(true);
     }
   } else if (type == chrome::NOTIFICATION_LOGIN_USER_CHANGED) {
     // A session is starting. Stop listening for user activity as it no longer
     // is a relevant criterion.
     if (ash::Shell::HasInstance())
       ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
     notification_registrar_.Remove(
         this, chrome::NOTIFICATION_LOGIN_USER_CHANGED,
         content::NotificationService::AllSources());
     login_screen_idle_timer_.reset();
   } else {
     NOTREACHED();
   }
 }

 // static
 void AutomaticRebootManager::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterIntegerPref(prefs::kUptimeLimit, 0);
   registry->RegisterBooleanPref(prefs::kRebootAfterUpdate, false);
 }

 void AutomaticRebootManager::Init(const SystemEventTimes& system_event_times) {
   const base::TimeDelta offset = clock_->NowTicks() - base::TimeTicks::Now();
   if (system_event_times.has_boot_time) {
     // Convert the time at which the device was booted to |clock_| ticks.
     boot_time_ = system_event_times.boot_time + offset;
     have_boot_time_ = true;
   }
   if (system_event_times.has_update_reboot_needed_time) {
     // Convert the time at which a reboot became necessary to |clock_| ticks.
     const base::TimeTicks update_reboot_needed_time =
         system_event_times.update_reboot_needed_time + offset;
     update_reboot_needed_time_ = update_reboot_needed_time;
     have_update_reboot_needed_time_ = true;
   } else {
     UpdateStatusChanged(
         DBusThreadManager::Get()->GetUpdateEngineClient()->GetLastStatus());
   }

   Reschedule();
 }

 void AutomaticRebootManager::Reschedule() {
   // Safeguard against reboot loops under error conditions: If the boot time is
   // unavailable because /proc/uptime could not be read, do nothing.
   if (!have_boot_time_)
     return;

   // Assume that no reboot has been requested.
   reboot_requested_ = false;

   const base::TimeDelta kZeroTimeDelta;
   AutomaticRebootManagerObserver::Reason reboot_reason =
       AutomaticRebootManagerObserver::REBOOT_REASON_UNKNOWN;

   // If an uptime limit is set, calculate the time at which it should cause a
   // reboot to be requested.
   const base::TimeDelta uptime_limit = base::TimeDelta::FromSeconds(
       local_state_registrar_.prefs()->GetInteger(prefs::kUptimeLimit));
   base::TimeTicks reboot_request_time = boot_time_ + uptime_limit;
   bool have_reboot_request_time = uptime_limit != kZeroTimeDelta;
   if (have_reboot_request_time)
     reboot_reason = AutomaticRebootManagerObserver::REBOOT_REASON_PERIODIC;

   // If the policy to automatically reboot after an update is enabled and an
   // update has been applied, set the time at which a reboot should be
   // requested to the minimum of its current value and the time when the reboot
   // became necessary.
   if (have_update_reboot_needed_time_ &&
       local_state_registrar_.prefs()->GetBoolean(prefs::kRebootAfterUpdate) &&
       (!have_reboot_request_time ||
        update_reboot_needed_time_ < reboot_request_time)) {
     reboot_request_time = update_reboot_needed_time_;
     have_reboot_request_time = true;
     reboot_reason = AutomaticRebootManagerObserver::REBOOT_REASON_OS_UPDATE;
   }

   // If no reboot should be requested, remove any grace period.
   if (!have_reboot_request_time) {
     grace_start_timer_.reset();
     grace_end_timer_.reset();
     return;
   }

   // Safeguard against reboot loops: Ensure that the uptime after which a reboot
   // is actually requested and the grace period begins is never less than
   // |kMinRebootUptimeMs|.
   const base::TimeTicks now = clock_->NowTicks();
   const base::TimeTicks grace_start_time = std::max(reboot_request_time,
       boot_time_ + base::TimeDelta::FromMilliseconds(kMinRebootUptimeMs));
   // Set up a timer for the start of the grace period. If the grace period
   // started in the past, the timer is still used with its delay set to zero.
   if (!grace_start_timer_)
     grace_start_timer_.reset(new base::OneShotTimer<AutomaticRebootManager>);
   grace_start_timer_->Start(FROM_HERE,
                             std::max(grace_start_time - now, kZeroTimeDelta),
                             base::Bind(&AutomaticRebootManager::RequestReboot,
                                        base::Unretained(this)));

   const base::TimeTicks grace_end_time = grace_start_time +
       base::TimeDelta::FromMilliseconds(kGracePeriodMs);
   // Set up a timer for the end of the grace period. If the grace period ended
   // in the past, the timer is still used with its delay set to zero.
   if (!grace_end_timer_)
     grace_end_timer_.reset(new base::OneShotTimer<AutomaticRebootManager>);
   grace_end_timer_->Start(FROM_HERE,
                           std::max(grace_end_time - now, kZeroTimeDelta),
                           base::Bind(&AutomaticRebootManager::Reboot,
                                      base::Unretained(this)));

   DCHECK_NE(AutomaticRebootManagerObserver::REBOOT_REASON_UNKNOWN,
             reboot_reason);
   FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
                     observers_,
                     OnRebootScheduled(reboot_reason));
 }

 void AutomaticRebootManager::RequestReboot() {
   reboot_requested_ = true;
   MaybeReboot(false);
 }

 void AutomaticRebootManager::MaybeReboot(bool ignore_session) {
   // Do not reboot if any of the following applies:
   // * No reboot has been requested.
   // * A user is interacting with the login screen.
   // * A session is in progress and |ignore_session| is not set.
   if (!reboot_requested_ ||
       (login_screen_idle_timer_ && login_screen_idle_timer_->IsRunning()) ||
       (!ignore_session && user_manager::UserManager::Get()->IsUserLoggedIn())) {
     return;
   }

   Reboot();
 }

 void AutomaticRebootManager::Reboot() {
   // If a non-kiosk-app session is in progress, do not reboot.
   if (user_manager::UserManager::Get()->IsUserLoggedIn() &&
       !user_manager::UserManager::Get()->IsLoggedInAsKioskApp()) {
     return;
   }

   login_screen_idle_timer_.reset();
   grace_start_timer_.reset();
   grace_end_timer_.reset();
   DBusThreadManager::Get()->GetPowerManagerClient()->RequestRestart();
 }

 }  // namespace system
 }  // namespace chromeos
	// Copyright (c) 2013 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/browser/chromeos/system/automatic_reboot_manager.h"

	#include <fcntl.h>
	#include <sys/stat.h>
	#include <sys/types.h>

	#include <algorithm>
	#include <string>

	#include "ash/shell.h"
	#include "base/bind.h"
	#include "base/bind_helpers.h"
	#include "base/callback.h"
	#include "base/file_util.h"
	#include "base/files/file_path.h"
	#include "base/files/scoped_file.h"
	#include "base/location.h"
	#include "base/logging.h"
	#include "base/memory/ref_counted.h"
	#include "base/path_service.h"
	#include "base/posix/eintr_wrapper.h"
	#include "base/prefs/pref_registry_simple.h"
	#include "base/prefs/pref_service.h"
	#include "base/single_thread_task_runner.h"
	#include "base/strings/string_number_conversions.h"
	#include "base/thread_task_runner_handle.h"
	#include "base/threading/sequenced_worker_pool.h"
	#include "base/threading/thread_restrictions.h"
	#include "base/time/tick_clock.h"
	#include "chrome/browser/browser_process.h"
	#include "chrome/browser/chrome_notification_types.h"
	#include "chrome/browser/chromeos/system/automatic_reboot_manager_observer.h"
	#include "chrome/common/pref_names.h"
	#include "chromeos/chromeos_paths.h"
	#include "chromeos/chromeos_switches.h"
	#include "chromeos/dbus/dbus_thread_manager.h"
	#include "components/user_manager/user_manager.h"
	#include "content/public/browser/browser_thread.h"
	#include "content/public/browser/notification_details.h"
	#include "content/public/browser/notification_service.h"
	#include "content/public/browser/notification_source.h"
	#include "ui/wm/core/user_activity_detector.h"

	namespace chromeos {
	namespace system {

	namespace {

	const int kMinRebootUptimeMs = 60 * 60 * 1000; // 1 hour.
	const int kLoginManagerIdleTimeoutMs = 60 * 1000; // 60 seconds.
	const int kGracePeriodMs = 24 * 60 * 60 * 1000; // 24 hours.
	const int kOneKilobyte = 1 << 10; // 1 kB in bytes.

	base::TimeDelta ReadTimeDeltaFromFile(const base::FilePath& path) {
	base::ThreadRestrictions::AssertIOAllowed();
	base::ScopedFD fd(
	HANDLE_EINTR(open(path.value().c_str(), O_RDONLY \| O_NOFOLLOW)));
	if (!fd.is_valid())
	return base::TimeDelta();

	std::string contents;
	char buffer[kOneKilobyte];
	ssize_t length;
	while ((length = HANDLE_EINTR(read(fd.get(), buffer, sizeof(buffer)))) > 0)
	contents.append(buffer, length);

	double seconds;
	if (!base::StringToDouble(contents.substr(0, contents.find(' ')), &seconds) \|\|
	seconds < 0.0) {
	return base::TimeDelta();
	}
	return base::TimeDelta::FromMilliseconds(seconds * 1000.0);
	}

	void GetSystemEventTimes(
	scoped_refptr<base::SingleThreadTaskRunner> reply_task_runner,
	base::Callback<void(
	const AutomaticRebootManager::SystemEventTimes&)> reply) {
	base::FilePath uptime_file;
	CHECK(PathService::Get(chromeos::FILE_UPTIME, &uptime_file));
	base::FilePath update_reboot_needed_uptime_file;
	CHECK(PathService::Get(chromeos::FILE_UPDATE_REBOOT_NEEDED_UPTIME,
	&update_reboot_needed_uptime_file));
	reply_task_runner->PostTask(FROM_HERE, base::Bind(reply,
	AutomaticRebootManager::SystemEventTimes(
	ReadTimeDeltaFromFile(uptime_file),
	ReadTimeDeltaFromFile(update_reboot_needed_uptime_file))));
	}

	void SaveUpdateRebootNeededUptime() {
	base::ThreadRestrictions::AssertIOAllowed();
	const base::TimeDelta kZeroTimeDelta;

	base::FilePath update_reboot_needed_uptime_file;
	CHECK(PathService::Get(chromeos::FILE_UPDATE_REBOOT_NEEDED_UPTIME,
	&update_reboot_needed_uptime_file));
	const base::TimeDelta last_update_reboot_needed_uptime =
	ReadTimeDeltaFromFile(update_reboot_needed_uptime_file);
	if (last_update_reboot_needed_uptime != kZeroTimeDelta)
	return;

	base::FilePath uptime_file;
	CHECK(PathService::Get(chromeos::FILE_UPTIME, &uptime_file));
	const base::TimeDelta uptime = ReadTimeDeltaFromFile(uptime_file);
	if (uptime == kZeroTimeDelta)
	return;

	base::ScopedFD fd(HANDLE_EINTR(
	open(update_reboot_needed_uptime_file.value().c_str(),
	O_CREAT \| O_WRONLY \| O_TRUNC \| O_NOFOLLOW,
	0666)));
	if (!fd.is_valid())
	return;

	std::string update_reboot_needed_uptime =
	base::DoubleToString(uptime.InSecondsF());
	base::WriteFileDescriptor(fd.get(), update_reboot_needed_uptime.c_str(),
	update_reboot_needed_uptime.size());
	}

	} // namespace

	AutomaticRebootManager::SystemEventTimes::SystemEventTimes()
	: has_boot_time(false),
	has_update_reboot_needed_time(false) {
	}

	AutomaticRebootManager::SystemEventTimes::SystemEventTimes(
	const base::TimeDelta& uptime,
	const base::TimeDelta& update_reboot_needed_uptime)
	: has_boot_time(false),
	has_update_reboot_needed_time(false) {
	const base::TimeDelta kZeroTimeDelta;
	if (uptime == kZeroTimeDelta)
	return;
	boot_time = base::TimeTicks::Now() - uptime;
	has_boot_time = true;
	if (update_reboot_needed_uptime == kZeroTimeDelta)
	return;
	// Calculate the time at which an update was applied and a reboot became
	// necessary in base::TimeTicks::Now() ticks.
	update_reboot_needed_time = boot_time + update_reboot_needed_uptime;
	has_update_reboot_needed_time = true;
	}

	AutomaticRebootManager::AutomaticRebootManager(
	scoped_ptr<base::TickClock> clock)
	: clock_(clock.Pass()),
	have_boot_time_(false),
	have_update_reboot_needed_time_(false),
	reboot_requested_(false),
	weak_ptr_factory_(this) {
	local_state_registrar_.Init(g_browser_process->local_state());
	local_state_registrar_.Add(prefs::kUptimeLimit,
	base::Bind(&AutomaticRebootManager::Reschedule,
	base::Unretained(this)));
	local_state_registrar_.Add(prefs::kRebootAfterUpdate,
	base::Bind(&AutomaticRebootManager::Reschedule,
	base::Unretained(this)));
	notification_registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
	content::NotificationService::AllSources());

	DBusThreadManager* dbus_thread_manager = DBusThreadManager::Get();
	dbus_thread_manager->GetPowerManagerClient()->AddObserver(this);
	dbus_thread_manager->GetUpdateEngineClient()->AddObserver(this);

	// If no user is logged in, a reboot may be performed whenever the user is
	// idle. Start listening for user activity to determine whether the user is
	// idle or not.
	if (!user_manager::UserManager::Get()->IsUserLoggedIn()) {
	if (ash::Shell::HasInstance())
	ash::Shell::GetInstance()->user_activity_detector()->AddObserver(this);
	notification_registrar_.Add(this, chrome::NOTIFICATION_LOGIN_USER_CHANGED,
	content::NotificationService::AllSources());
	login_screen_idle_timer_.reset(
	new base::OneShotTimer<AutomaticRebootManager>);
	OnUserActivity(NULL);
	}

	// In a regular browser, base::ThreadTaskRunnerHandle::Get() and
	// base::MessageLoopProxy::current() return pointers to the same object.
	// In unit tests, using base::ThreadTaskRunnerHandle::Get() has the advantage
	// that it allows a custom base::SingleThreadTaskRunner to be injected.
	content::BrowserThread::GetBlockingPool()->PostWorkerTaskWithShutdownBehavior(
	FROM_HERE,
	base::Bind(&GetSystemEventTimes,
	base::ThreadTaskRunnerHandle::Get(),
	base::Bind(&AutomaticRebootManager::Init,
	weak_ptr_factory_.GetWeakPtr())),
	base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
	}

	AutomaticRebootManager::~AutomaticRebootManager() {
	FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
	observers_,
	WillDestroyAutomaticRebootManager());

	DBusThreadManager* dbus_thread_manager = DBusThreadManager::Get();
	dbus_thread_manager->GetPowerManagerClient()->RemoveObserver(this);
	dbus_thread_manager->GetUpdateEngineClient()->RemoveObserver(this);
	if (ash::Shell::HasInstance())
	ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
	}

	void AutomaticRebootManager::AddObserver(
	AutomaticRebootManagerObserver* observer) {
	observers_.AddObserver(observer);
	}

	void AutomaticRebootManager::RemoveObserver(
	AutomaticRebootManagerObserver* observer) {
	observers_.RemoveObserver(observer);
	}

	void AutomaticRebootManager::SuspendDone(
	const base::TimeDelta& sleep_duration) {
	MaybeReboot(true);
	}

	void AutomaticRebootManager::UpdateStatusChanged(
	const UpdateEngineClient::Status& status) {
	// Ignore repeated notifications that a reboot is necessary. This is important
	// so that only the time of the first notification is taken into account and
	// repeated notifications do not postpone the reboot request and grace period.
	if (status.status != UpdateEngineClient::UPDATE_STATUS_UPDATED_NEED_REBOOT \|\|
	!have_boot_time_ \|\| have_update_reboot_needed_time_) {
	return;
	}

	content::BrowserThread::PostBlockingPoolTask(
	FROM_HERE, base::Bind(&SaveUpdateRebootNeededUptime));

	update_reboot_needed_time_ = clock_->NowTicks();
	have_update_reboot_needed_time_ = true;

	Reschedule();
	}

	void AutomaticRebootManager::OnUserActivity(const ui::Event* event) {
	if (!login_screen_idle_timer_)
	return;

	// Destroying and re-creating the timer ensures that Start() posts a fresh
	// task with a delay of exactly \|kLoginManagerIdleTimeoutMs\|, ensuring that
	// the timer fires predictably in tests.
	login_screen_idle_timer_.reset(
	new base::OneShotTimer<AutomaticRebootManager>);
	login_screen_idle_timer_->Start(
	FROM_HERE,
	base::TimeDelta::FromMilliseconds(kLoginManagerIdleTimeoutMs),
	base::Bind(&AutomaticRebootManager::MaybeReboot,
	base::Unretained(this),
	false));
	}

	void AutomaticRebootManager::Observe(
	int type,
	const content::NotificationSource& source,
	const content::NotificationDetails& details) {
	if (type == chrome::NOTIFICATION_APP_TERMINATING) {
	if (user_manager::UserManager::Get()->IsUserLoggedIn()) {
	// The browser is terminating during a session, either because the session
	// is ending or because the browser is being restarted.
	MaybeReboot(true);
	}
	} else if (type == chrome::NOTIFICATION_LOGIN_USER_CHANGED) {
	// A session is starting. Stop listening for user activity as it no longer
	// is a relevant criterion.
	if (ash::Shell::HasInstance())
	ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
	notification_registrar_.Remove(
	this, chrome::NOTIFICATION_LOGIN_USER_CHANGED,
	content::NotificationService::AllSources());
	login_screen_idle_timer_.reset();
	} else {
	NOTREACHED();
	}
	}

	// static
	void AutomaticRebootManager::RegisterPrefs(PrefRegistrySimple* registry) {
	registry->RegisterIntegerPref(prefs::kUptimeLimit, 0);
	registry->RegisterBooleanPref(prefs::kRebootAfterUpdate, false);
	}

	void AutomaticRebootManager::Init(const SystemEventTimes& system_event_times) {
	const base::TimeDelta offset = clock_->NowTicks() - base::TimeTicks::Now();
	if (system_event_times.has_boot_time) {
	// Convert the time at which the device was booted to \|clock_\| ticks.
	boot_time_ = system_event_times.boot_time + offset;
	have_boot_time_ = true;
	}
	if (system_event_times.has_update_reboot_needed_time) {
	// Convert the time at which a reboot became necessary to \|clock_\| ticks.
	const base::TimeTicks update_reboot_needed_time =
	system_event_times.update_reboot_needed_time + offset;
	update_reboot_needed_time_ = update_reboot_needed_time;
	have_update_reboot_needed_time_ = true;
	} else {
	UpdateStatusChanged(
	DBusThreadManager::Get()->GetUpdateEngineClient()->GetLastStatus());
	}

	Reschedule();
	}

	void AutomaticRebootManager::Reschedule() {
	// Safeguard against reboot loops under error conditions: If the boot time is
	// unavailable because /proc/uptime could not be read, do nothing.
	if (!have_boot_time_)
	return;

	// Assume that no reboot has been requested.
	reboot_requested_ = false;

	const base::TimeDelta kZeroTimeDelta;
	AutomaticRebootManagerObserver::Reason reboot_reason =
	AutomaticRebootManagerObserver::REBOOT_REASON_UNKNOWN;

	// If an uptime limit is set, calculate the time at which it should cause a
	// reboot to be requested.
	const base::TimeDelta uptime_limit = base::TimeDelta::FromSeconds(
	local_state_registrar_.prefs()->GetInteger(prefs::kUptimeLimit));
	base::TimeTicks reboot_request_time = boot_time_ + uptime_limit;
	bool have_reboot_request_time = uptime_limit != kZeroTimeDelta;
	if (have_reboot_request_time)
	reboot_reason = AutomaticRebootManagerObserver::REBOOT_REASON_PERIODIC;

	// If the policy to automatically reboot after an update is enabled and an
	// update has been applied, set the time at which a reboot should be
	// requested to the minimum of its current value and the time when the reboot
	// became necessary.
	if (have_update_reboot_needed_time_ &&
	local_state_registrar_.prefs()->GetBoolean(prefs::kRebootAfterUpdate) &&
	(!have_reboot_request_time \|\|
	update_reboot_needed_time_ < reboot_request_time)) {
	reboot_request_time = update_reboot_needed_time_;
	have_reboot_request_time = true;
	reboot_reason = AutomaticRebootManagerObserver::REBOOT_REASON_OS_UPDATE;
	}

	// If no reboot should be requested, remove any grace period.
	if (!have_reboot_request_time) {
	grace_start_timer_.reset();
	grace_end_timer_.reset();
	return;
	}

	// Safeguard against reboot loops: Ensure that the uptime after which a reboot
	// is actually requested and the grace period begins is never less than
	// \|kMinRebootUptimeMs\|.
	const base::TimeTicks now = clock_->NowTicks();
	const base::TimeTicks grace_start_time = std::max(reboot_request_time,
	boot_time_ + base::TimeDelta::FromMilliseconds(kMinRebootUptimeMs));
	// Set up a timer for the start of the grace period. If the grace period
	// started in the past, the timer is still used with its delay set to zero.
	if (!grace_start_timer_)
	grace_start_timer_.reset(new base::OneShotTimer<AutomaticRebootManager>);
	grace_start_timer_->Start(FROM_HERE,
	std::max(grace_start_time - now, kZeroTimeDelta),
	base::Bind(&AutomaticRebootManager::RequestReboot,
	base::Unretained(this)));

	const base::TimeTicks grace_end_time = grace_start_time +
	base::TimeDelta::FromMilliseconds(kGracePeriodMs);
	// Set up a timer for the end of the grace period. If the grace period ended
	// in the past, the timer is still used with its delay set to zero.
	if (!grace_end_timer_)
	grace_end_timer_.reset(new base::OneShotTimer<AutomaticRebootManager>);
	grace_end_timer_->Start(FROM_HERE,
	std::max(grace_end_time - now, kZeroTimeDelta),
	base::Bind(&AutomaticRebootManager::Reboot,
	base::Unretained(this)));

	DCHECK_NE(AutomaticRebootManagerObserver::REBOOT_REASON_UNKNOWN,
	reboot_reason);
	FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
	observers_,
	OnRebootScheduled(reboot_reason));
	}

	void AutomaticRebootManager::RequestReboot() {
	reboot_requested_ = true;
	MaybeReboot(false);
	}

	void AutomaticRebootManager::MaybeReboot(bool ignore_session) {
	// Do not reboot if any of the following applies:
	// * No reboot has been requested.
	// * A user is interacting with the login screen.
	// * A session is in progress and \|ignore_session\| is not set.
	if (!reboot_requested_ \|\|
	(login_screen_idle_timer_ && login_screen_idle_timer_->IsRunning()) \|\|
	(!ignore_session && user_manager::UserManager::Get()->IsUserLoggedIn())) {
	return;
	}

	Reboot();
	}

	void AutomaticRebootManager::Reboot() {
	// If a non-kiosk-app session is in progress, do not reboot.
	if (user_manager::UserManager::Get()->IsUserLoggedIn() &&
	!user_manager::UserManager::Get()->IsLoggedInAsKioskApp()) {
	return;
	}

	login_screen_idle_timer_.reset();
	grace_start_timer_.reset();
	grace_end_timer_.reset();
	DBusThreadManager::Get()->GetPowerManagerClient()->RequestRestart();
	}

	} // namespace system
	} // namespace chromeos