Make the SystemMonitor observer list thread safe....

base/system_monitor.cc

 // 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"
 
 namespace base {
 
+// The amount of time (in ms) to wait before running the initial
+// battery check.
+static int kDelayedBatteryCheckMs = 10 * 1000;
+
 SystemMonitor::SystemMonitor()
-    : battery_in_use_(IsBatteryPower()),
+    : 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 PowerStateEvent:
+    case POWER_STATE_EVENT:
       {
         bool on_battery = IsBatteryPower();
         if (on_battery != battery_in_use_) {
           battery_in_use_ = on_battery;
           NotifyPowerStateChange();
         }
       }
       break;
-    case ResumeEvent:
+    case RESUME_EVENT:
       if (suspended_) {
         suspended_ = false;
         NotifyResume();
       }
       break;
-    case SuspendEvent:
+    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, this);
+}
+
+void SystemMonitor::NotifySuspend() {
+  LOG(INFO) << L"Power Suspending";
+  observer_list_->Notify(&PowerObserver::OnSuspend, this);
+}
+
+void SystemMonitor::NotifyResume() {
+  LOG(INFO) << L"Power Resuming";
+  observer_list_->Notify(&PowerObserver::OnResume, this);
+}
+
+void SystemMonitor::Start() {
+  SystemMonitor* monitor = Get();
+  monitor->delayed_battery_check_.Start(
+      TimeDelta::FromMilliseconds(kDelayedBatteryCheckMs), monitor,
+      &SystemMonitor::BatteryCheck);
+}
+
+void SystemMonitor::BatteryCheck() {
+  ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
+}
+
 } // namespace base