Revert of Attempting to resolve a race condition with PowerMonitor

base/power_monitor/power_monitor.cc

 // Copyright 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 "base/power_monitor/power_monitor.h"
-
-#include "base/lazy_instance.h"
 #include "base/power_monitor/power_monitor_source.h"
-#include "base/synchronization/lock.h"
 
 namespace base {
 
-class PowerMonitorImpl;
+static PowerMonitor* g_power_monitor = NULL;
 
-LazyInstance<Lock>::Leaky g_power_monitor_lock = LAZY_INSTANCE_INITIALIZER;
-static PowerMonitorImpl* g_power_monitor = NULL;
-
-// A class used to monitor the power state change and notify the observers about
-// the change event.
-class BASE_EXPORT PowerMonitorImpl {
- public:
-  explicit PowerMonitorImpl(scoped_ptr<PowerMonitorSource> source)
-      : observers_(new ObserverListThreadSafe<PowerObserver>()),
-      source_(source.Pass()) { }
-
-  ~PowerMonitorImpl()  { }
-
-  scoped_refptr<ObserverListThreadSafe<PowerObserver> > observers_;
-  scoped_ptr<PowerMonitorSource> source_;
-
-  DISALLOW_COPY_AND_ASSIGN(PowerMonitorImpl);
-};
-
-void PowerMonitor::Initialize(scoped_ptr<PowerMonitorSource> source) {
-  AutoLock(g_power_monitor_lock.Get());
+PowerMonitor::PowerMonitor(scoped_ptr<PowerMonitorSource> source)
+    : observers_(new ObserverListThreadSafe<PowerObserver>()),
+      source_(source.Pass()) {
   DCHECK(!g_power_monitor);
-  g_power_monitor = new PowerMonitorImpl(source.Pass());
+  g_power_monitor = this;
 }
 
-void PowerMonitor::ShutdownForTesting() {
-  AutoLock(g_power_monitor_lock.Get());
-  if (g_power_monitor) {
-    delete g_power_monitor;
-    g_power_monitor = NULL;
-  }
+PowerMonitor::~PowerMonitor() {
+  DCHECK_EQ(this, g_power_monitor);
+  g_power_monitor = NULL;
 }
 
-bool PowerMonitor::IsInitialized() {
-  AutoLock(g_power_monitor_lock.Get());
-  return g_power_monitor != NULL;
+// static
+PowerMonitor* PowerMonitor::Get() {
+  return g_power_monitor;
 }
 
-bool PowerMonitor::AddObserver(PowerObserver* observer) {
-  AutoLock(g_power_monitor_lock.Get());
-  if (!g_power_monitor)
-    return false;
-  g_power_monitor->observers_->AddObserver(observer);
-  return true;
+void PowerMonitor::AddObserver(PowerObserver* obs) {
+  observers_->AddObserver(obs);
 }
 
-bool PowerMonitor::RemoveObserver(PowerObserver* observer) {
-  AutoLock(g_power_monitor_lock.Get());
-  if (!g_power_monitor)
-    return false;
-  g_power_monitor->observers_->RemoveObserver(observer);
-  return true;
+void PowerMonitor::RemoveObserver(PowerObserver* obs) {
+  observers_->RemoveObserver(obs);
+}
+
+PowerMonitorSource* PowerMonitor::Source() {
+  return source_.get();
 }
 
 bool PowerMonitor::IsOnBatteryPower() {
-  g_power_monitor_lock.Get().AssertAcquired();
-  if (!g_power_monitor)
-    return false;
-  return g_power_monitor->source_->IsOnBatteryPower();
-}
-
-Lock* PowerMonitor::GetLock() {
-  return &g_power_monitor_lock.Get();
-}
-
-bool PowerMonitor::IsInitializedLocked() {
-  g_power_monitor_lock.Get().AssertAcquired();
-  return g_power_monitor != NULL;
-}
-
-PowerMonitorSource* PowerMonitor::GetSource() {
-  g_power_monitor_lock.Get().AssertAcquired();
-  return g_power_monitor->source_.get();
+  return source_->IsOnBatteryPower();
 }
 
 void PowerMonitor::NotifyPowerStateChange(bool battery_in_use) {
   DVLOG(1) << "PowerStateChange: " << (battery_in_use ? "On" : "Off")
            << " battery";
-  g_power_monitor_lock.Get().AssertAcquired();
-  g_power_monitor->observers_->Notify(&PowerObserver::OnPowerStateChange,
-      battery_in_use);
+  observers_->Notify(&PowerObserver::OnPowerStateChange, battery_in_use);
 }
 
 void PowerMonitor::NotifySuspend() {
   DVLOG(1) << "Power Suspending";
-  g_power_monitor_lock.Get().AssertAcquired();
-  g_power_monitor->observers_->Notify(&PowerObserver::OnSuspend);
+  observers_->Notify(&PowerObserver::OnSuspend);
 }
 
 void PowerMonitor::NotifyResume() {
   DVLOG(1) << "Power Resuming";
-  g_power_monitor_lock.Get().AssertAcquired();
-  g_power_monitor->observers_->Notify(&PowerObserver::OnResume);
+  observers_->Notify(&PowerObserver::OnResume);
 }
 
 }  // namespace base