Make SystemMonitor not a Singleton and move it out of base

SystemMonitor makes an assumption that through its lifetime a MessageLoop exists and stays the same. It is difficult and error-prone to satisfy that when it is a Singleton. It has caused problems in the past.

Additionally, extract HighResoltionTimerManager out of time_win.cc, eliminating yet another Singleton.

TEST=none
BUG=none

Review URL: http://codereview.chromium.org/431008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33214 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 19 insertions, 461 deletions

diff --git a/base/base.gyp b/base/base.gyp
index 7238928..23b85b1 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -321,10 +321,6 @@
         'sys_string_conversions_linux.cc',
         'sys_string_conversions_mac.mm',
         'sys_string_conversions_win.cc',
-        'system_monitor.cc',
-        'system_monitor.h',
-        'system_monitor_posix.cc',
-        'system_monitor_win.cc',
         'task.h',
         'thread.cc',
         'thread.h',
@@ -654,7 +650,6 @@
         'sys_info_unittest.cc',
         'sys_string_conversions_mac_unittest.mm',
         'sys_string_conversions_unittest.cc',
-        'system_monitor_unittest.cc',
         'task_unittest.cc',
         'thread_collision_warner_unittest.cc',
         'thread_local_storage_unittest.cc',
diff --git a/base/system_monitor.cc b/base/system_monitor.cc
deleted file mode 100644
index 44cdce5..0000000
--- a/base/system_monitor.cc
+++ /dev/null
@@ -1,98 +0,0 @@
-// Copyright (c) 2008 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 "base/system_monitor.h"
-#include "base/logging.h"
-#include "base/message_loop.h"
-#include "base/singleton.h"
-
-namespace base {
-
-#if defined(ENABLE_BATTERY_MONITORING)
-// The amount of time (in ms) to wait before running the initial
-// battery check.
-static int kDelayedBatteryCheckMs = 10 * 1000;
-#endif  // defined(ENABLE_BATTERY_MONITORING)
-
-SystemMonitor::SystemMonitor()
-    : battery_in_use_(false),
-      suspended_(false) {
-  observer_list_ = new ObserverListThreadSafe<PowerObserver>();
-}
-
-void SystemMonitor::ProcessPowerMessage(PowerEvent event_id) {
-  // Suppress duplicate notifications.  Some platforms may
-  // send multiple notifications of the same event.
-  switch (event_id) {
-    case POWER_STATE_EVENT:
-      {
-        bool on_battery = IsBatteryPower();
-        if (on_battery != battery_in_use_) {
-          battery_in_use_ = on_battery;
-          NotifyPowerStateChange();
-        }
-      }
-      break;
-    case RESUME_EVENT:
-      if (suspended_) {
-        suspended_ = false;
-        NotifyResume();
-      }
-      break;
-    case SUSPEND_EVENT:
-      if (!suspended_) {
-        suspended_ = true;
-        NotifySuspend();
-      }
-      break;
-  }
-}
-
-void SystemMonitor::AddObserver(PowerObserver* obs) {
-  observer_list_->AddObserver(obs);
-}
-
-void SystemMonitor::RemoveObserver(PowerObserver* obs) {
-  observer_list_->RemoveObserver(obs);
-}
-
-void SystemMonitor::NotifyPowerStateChange() {
-  LOG(INFO) << L"PowerStateChange: "
-           << (BatteryPower() ? L"On" : L"Off") << L" battery";
-  observer_list_->Notify(&PowerObserver::OnPowerStateChange, BatteryPower());
-}
-
-void SystemMonitor::NotifySuspend() {
-  LOG(INFO) << L"Power Suspending";
-  observer_list_->Notify(&PowerObserver::OnSuspend);
-}
-
-void SystemMonitor::NotifyResume() {
-  LOG(INFO) << L"Power Resuming";
-  observer_list_->Notify(&PowerObserver::OnResume);
-}
-
-// static
-SystemMonitor* SystemMonitor::Get() {
-  // Uses the LeakySingletonTrait because cleanup is optional.
-  return
-      Singleton<SystemMonitor, LeakySingletonTraits<SystemMonitor> >::get();
-}
-
-// static
-void SystemMonitor::Start() {
-#if defined(ENABLE_BATTERY_MONITORING)
-  DCHECK(MessageLoop::current());  // Can't call start too early.
-  SystemMonitor* monitor = Get();
-  monitor->delayed_battery_check_.Start(
-      TimeDelta::FromMilliseconds(kDelayedBatteryCheckMs), monitor,
-      &SystemMonitor::BatteryCheck);
-#endif  // defined(ENABLE_BATTERY_MONITORING)
-}
-
-void SystemMonitor::BatteryCheck() {
-  ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
-}
-
-} // namespace base
diff --git a/base/system_monitor.h b/base/system_monitor.h
deleted file mode 100644
index 71d8436..0000000
--- a/base/system_monitor.h
+++ /dev/null
@@ -1,129 +0,0 @@
-// Copyright (c) 2009 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.
-
-#ifndef BASE_SYSTEM_MONITOR_H_
-#define BASE_SYSTEM_MONITOR_H_
-
-#include "build/build_config.h"
-
-// Windows HiRes timers drain the battery faster so we need to know the battery
-// status.  This isn't true for other platforms.
-#if defined(OS_WIN)
-#define ENABLE_BATTERY_MONITORING 1
-#else
-#undef ENABLE_BATTERY_MONITORING
-#endif  // !OS_WIN
-
-#include "base/observer_list_threadsafe.h"
-#if defined(ENABLE_BATTERY_MONITORING)
-#include "base/timer.h"
-#endif  // defined(ENABLE_BATTERY_MONITORING)
-
-namespace base {
-
-// Class for monitoring various system-related subsystems
-// such as power management, network status, etc.
-// TODO(mbelshe):  Add support beyond just power management.
-class SystemMonitor {
- public:
-  // Retrieves the Singleton.
-  static SystemMonitor* Get();
-
-  // Start the System Monitor within a process.  This method
-  // is provided so that the battery check can be deferred.
-  // The MessageLoop must be started before calling this
-  // method.
-  // This is a no-op on platforms for which ENABLE_BATTERY_MONITORING is
-  // disabled.
-  static void Start();
-
-  //
-  // Power-related APIs
-  //
-
-  // Is the computer currently on battery power.
-  // Can be called on any thread.
-  bool BatteryPower() const {
-    // Using a lock here is not necessary for just a bool.
-    return battery_in_use_;
-  }
-
-  // Normalized list of power events.
-  enum PowerEvent {
-    POWER_STATE_EVENT,  // The Power status of the system has changed.
-    SUSPEND_EVENT,      // The system is being suspended.
-    RESUME_EVENT        // The system is being resumed.
-  };
-
-  // Callbacks will be called on the thread which creates the SystemMonitor.
-  // During the callback, Add/RemoveObserver will block until the callbacks
-  // are finished. Observers should implement quick callback functions; if
-  // lengthy operations are needed, the observer should take care to invoke
-  // the operation on an appropriate thread.
-  class PowerObserver {
-   public:
-    // Notification of a change in power status of the computer, such
-    // as from switching between battery and A/C power.
-    virtual void OnPowerStateChange(bool on_battery_power) {}
-
-    // Notification that the system is suspending.
-    virtual void OnSuspend() {}
-
-    // Notification that the system is resuming.
-    virtual void OnResume() {}
-  };
-
-  // Add a new observer.
-  // Can be called from any thread.
-  // Must not be called from within a notification callback.
-  void AddObserver(PowerObserver* obs);
-
-  // Remove an existing observer.
-  // Can be called from any thread.
-  // Must not be called from within a notification callback.
-  void RemoveObserver(PowerObserver* obs);
-
-#if defined(OS_WIN)
-  // Windows-specific handling of a WM_POWERBROADCAST message.
-  // Embedders of this API should hook their top-level window
-  // message loop and forward WM_POWERBROADCAST through this call.
-  void ProcessWmPowerBroadcastMessage(int event_id);
-#endif
-
-  // Cross-platform handling of a power event.
-  void ProcessPowerMessage(PowerEvent event_id);
-
-  // Constructor.
-  // Don't use this; access SystemMonitor via the Singleton.
-  SystemMonitor();
-
- private:
-  // Platform-specific method to check whether the system is currently
-  // running on battery power.  Returns true if running on batteries,
-  // false otherwise.
-  bool IsBatteryPower();
-
-  // Checks the battery status and notifies observers if the battery
-  // status has changed.
-  void BatteryCheck();
-
-  // Functions to trigger notifications.
-  void NotifyPowerStateChange();
-  void NotifySuspend();
-  void NotifyResume();
-
-  scoped_refptr<ObserverListThreadSafe<PowerObserver> > observer_list_;
-  bool battery_in_use_;
-  bool suspended_;
-
-#if defined(ENABLE_BATTERY_MONITORING)
-  base::OneShotTimer<SystemMonitor> delayed_battery_check_;
-#endif
-
-  DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
-};
-
-}
-
-#endif  // BASE_SYSTEM_MONITOR_H_
diff --git a/base/system_monitor_posix.cc b/base/system_monitor_posix.cc
deleted file mode 100644
index a4a118c..0000000
--- a/base/system_monitor_posix.cc
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright (c) 2008 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 "base/system_monitor.h"
-
-namespace base {
-
-bool SystemMonitor::IsBatteryPower() {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-} // namespace base
diff --git a/base/system_monitor_unittest.cc b/base/system_monitor_unittest.cc
deleted file mode 100644
index 7ba3a6b..0000000
--- a/base/system_monitor_unittest.cc
+++ /dev/null
@@ -1,86 +0,0 @@
-// Copyright (c) 2009 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 "base/system_monitor.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-class PowerTest : public base::SystemMonitor::PowerObserver {
- public:
-  PowerTest()
-      : battery_(false),
-        power_state_changes_(0),
-        suspends_(0),
-        resumes_(0) {};
-
-  // PowerObserver callbacks.
-  void OnPowerStateChange(bool on_battery_power) {
-    power_state_changes_++;
-  }
-
-  void OnSuspend() {
-    suspends_++;
-  }
-
-  void OnResume() {
-    resumes_++;
-  }
-
-  // Test status counts.
-  bool battery() { return battery_; }
-  int power_state_changes() { return power_state_changes_; }
-  int suspends() { return suspends_; }
-  int resumes() { return resumes_; }
-
- private:
-  bool battery_;   // Do we currently think we're on battery power.
-  int power_state_changes_;  // Count of OnPowerStateChange notifications.
-  int suspends_;  // Count of OnSuspend notifications.
-  int resumes_;  // Count of OnResume notifications.
-};
-
-TEST(SystemMonitor, PowerNotifications) {
-  const int kObservers = 5;
-
-  // Initialize a message loop for this to run on.
-  MessageLoop loop;
-  // Initialize time() since it registers as a SystemMonitor observer.
-  base::Time now = base::Time::Now();
-
-  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
-  PowerTest test[kObservers];
-  for (int index = 0; index < kObservers; ++index)
-    system_monitor->AddObserver(&test[index]);
-
-  // Send a bunch of power changes.  Since the battery power hasn't
-  // actually changed, we shouldn't get notifications.
-  for (int index = 0; index < 5; index++) {
-    system_monitor->ProcessPowerMessage(base::SystemMonitor::POWER_STATE_EVENT);
-    EXPECT_EQ(test[0].power_state_changes(), 0);
-  }
-
-  // Sending resume when not suspended should have no effect.
-  system_monitor->ProcessPowerMessage(base::SystemMonitor::RESUME_EVENT);
-  loop.RunAllPending();
-  EXPECT_EQ(test[0].resumes(), 0);
-
-  // Pretend we suspended.
-  system_monitor->ProcessPowerMessage(base::SystemMonitor::SUSPEND_EVENT);
-  loop.RunAllPending();
-  EXPECT_EQ(test[0].suspends(), 1);
-
-  // Send a second suspend notification.  This should be suppressed.
-  system_monitor->ProcessPowerMessage(base::SystemMonitor::SUSPEND_EVENT);
-  loop.RunAllPending();
-  EXPECT_EQ(test[0].suspends(), 1);
-
-  // Pretend we were awakened.
-  system_monitor->ProcessPowerMessage(base::SystemMonitor::RESUME_EVENT);
-  loop.RunAllPending();
-  EXPECT_EQ(test[0].resumes(), 1);
-
-  // Send a duplicate resume notification.  This should be suppressed.
-  system_monitor->ProcessPowerMessage(base::SystemMonitor::RESUME_EVENT);
-  loop.RunAllPending();
-  EXPECT_EQ(test[0].resumes(), 1);
-}
diff --git a/base/system_monitor_win.cc b/base/system_monitor_win.cc
deleted file mode 100644
index 8a2d8c9..0000000
--- a/base/system_monitor_win.cc
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright (c) 2008 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 "base/system_monitor.h"
-
-namespace base {
-
-void SystemMonitor::ProcessWmPowerBroadcastMessage(int event_id) {
-  PowerEvent power_event;
-  switch (event_id) {
-    case PBT_APMPOWERSTATUSCHANGE:  // The power status changed.
-      power_event = POWER_STATE_EVENT;
-      break;
-    case PBT_APMRESUMEAUTOMATIC:  // Resume from suspend.
-    //case PBT_APMRESUMESUSPEND:  // User-initiated resume from suspend.
-                                  // We don't notify for this latter event
-                                  // because if it occurs it is always sent as a
-                                  // second event after PBT_APMRESUMEAUTOMATIC.
-      power_event = RESUME_EVENT;
-      break;
-    case PBT_APMSUSPEND:  // System has been suspended.
-      power_event = SUSPEND_EVENT;
-      break;
-    default:
-      return;
-
-    // Other Power Events:
-    // PBT_APMBATTERYLOW - removed in Vista.
-    // PBT_APMOEMEVENT - removed in Vista.
-    // PBT_APMQUERYSUSPEND - removed in Vista.
-    // PBT_APMQUERYSUSPENDFAILED - removed in Vista.
-    // PBT_APMRESUMECRITICAL - removed in Vista.
-    // PBT_POWERSETTINGCHANGE - user changed the power settings.
-  }
-  ProcessPowerMessage(power_event);
-}
-
-// Function to query the system to see if it is currently running on
-// battery power.  Returns true if running on battery.
-bool SystemMonitor::IsBatteryPower() {
-  SYSTEM_POWER_STATUS status;
-  if (!GetSystemPowerStatus(&status)) {
-    LOG(ERROR) << "GetSystemPowerStatus failed: " << GetLastError();
-    return false;
-  }
-  return (status.ACLineStatus == 0);
-}
-
-
-
-} // namespace base
diff --git a/base/test/test_suite.h b/base/test/test_suite.h
index 44e8511..2566b1a 100644
--- a/base/test/test_suite.h
+++ b/base/test/test_suite.h
@@ -182,10 +182,10 @@ class TestSuite {
 
     CHECK(base::EnableInProcessStackDumping());
 #if defined(OS_WIN)
-    // For unit tests we turn on the high resolution timer and disable
-    // base::Time's use of SystemMonitor. Tests create and destroy the message
-    // loop, which causes a crash with SystemMonitor (http://crbug.com/12187).
-    base::Time::EnableHiResClockForTests();
+    // Make sure we run with high resolution timer to minimize differences
+    // between production code and test code.
+    bool result = base::Time::UseHighResolutionTimer(true);
+    CHECK(result);
 
     // In some cases, we do not want to see standard error dialogs.
     if (!IsDebuggerPresent() &&
diff --git a/base/time.h b/base/time.h
index 8cd752a..33ab227 100644
--- a/base/time.h
+++ b/base/time.h
@@ -242,12 +242,9 @@ class Time {
   static Time FromFileTime(FILETIME ft);
   FILETIME ToFileTime() const;
 
-  // Monitor system power state and disable high resolution timer when we're
-  // on battery. See time_win.cc for more details.
-  static void StartSystemMonitorObserver();
-
-  // Enable high resolution timer unconditionally. Only for test code.
-  static void EnableHiResClockForTests();
+  // Enable or disable Windows high resolution timer. For more details
+  // see comments in time_win.cc. Returns true on success.
+  static bool UseHighResolutionTimer(bool use);
 #endif
 
   // Converts an exploded structure representing either the local time or UTC
diff --git a/base/time_win.cc b/base/time_win.cc
index 9fdcab1..eedf468 100644
--- a/base/time_win.cc
+++ b/base/time_win.cc
@@ -45,7 +45,6 @@
 #include "base/logging.h"
 #include "base/cpu.h"
 #include "base/singleton.h"
-#include "base/system_monitor.h"
 
 using base::Time;
 using base::TimeDelta;
@@ -88,65 +87,6 @@ void InitializeClock() {
   initial_time = CurrentWallclockMicroseconds();
 }
 
-class HighResolutionTimerManager : public base::SystemMonitor::PowerObserver {
- public:
-  ~HighResolutionTimerManager() {
-    StopMonitoring();
-    UseHiResClock(false);
-  }
-
-  void Enable() {
-    StopMonitoring();
-    UseHiResClock(true);
-  }
-
-  void StartMonitoring() {
-    if (is_monitoring_)
-      return;
-    is_monitoring_ = true;
-    base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
-    system_monitor->AddObserver(this);
-    UseHiResClock(!system_monitor->BatteryPower());
-  }
-
-  void StopMonitoring() {
-    if (!is_monitoring_)
-      return;
-    is_monitoring_ = false;
-    base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
-    if (system_monitor)
-      system_monitor->RemoveObserver(this);
-  }
-
-  // Interfaces for monitoring Power changes.
-  void OnPowerStateChange(bool on_battery_power) {
-    UseHiResClock(!on_battery_power);
-  }
-
- private:
-  HighResolutionTimerManager()
-      : is_monitoring_(false),
-        hi_res_clock_enabled_(false) {
-  }
-  friend struct DefaultSingletonTraits<HighResolutionTimerManager>;
-
-  // Enable or disable the faster multimedia timer.
-  void UseHiResClock(bool enabled) {
-    if (enabled == hi_res_clock_enabled_)
-      return;
-    if (enabled)
-      timeBeginPeriod(1);
-    else
-      timeEndPeriod(1);
-    hi_res_clock_enabled_ = enabled;
-  }
-
-  bool is_monitoring_;
-  bool hi_res_clock_enabled_;
-
-  DISALLOW_COPY_AND_ASSIGN(HighResolutionTimerManager);
-};
-
 }  // namespace
 
 // Time -----------------------------------------------------------------------
@@ -208,13 +148,18 @@ FILETIME Time::ToFileTime() const {
 }
 
 // static
-void Time::StartSystemMonitorObserver() {
-  Singleton<HighResolutionTimerManager>()->StartMonitoring();
-}
-
-// static
-void Time::EnableHiResClockForTests() {
-  Singleton<HighResolutionTimerManager>()->Enable();
+bool Time::UseHighResolutionTimer(bool use) {
+  // TODO(mbelshe): Make sure that switching the system timer resolution
+  // doesn't break Timer firing order etc. An example test would be to have
+  // two threads. One would have a bunch of timers, and another would turn the
+  // high resolution timer on and off.
+
+  MMRESULT result;
+  if (use)
+    result = timeBeginPeriod(1);
+  else
+    result = timeEndPeriod(1);
+  return (result == TIMERR_NOERROR);
 }
 
 // static