Attempting to resolve a race condition with PowerMonitor

base/power_monitor/power_monitor_source.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_source.h"
 
 #include "base/power_monitor/power_monitor.h"
 
 namespace base {
 
 PowerMonitorSource::PowerMonitorSource()
     : on_battery_power_(false),
       suspended_(false) {
 }
 
 PowerMonitorSource::~PowerMonitorSource() {
 }
 
 bool PowerMonitorSource::IsOnBatteryPower() {
   AutoLock auto_lock(battery_lock_);
   return on_battery_power_;
 }
 
 void PowerMonitorSource::ProcessPowerEvent(PowerEvent event_id) {
-  PowerMonitor* monitor = PowerMonitor::Get();
+  AutoLock lock(*PowerMonitor::GetSingletonLock());
+  PowerMonitor* monitor = PowerMonitor::GetSingleton();
   if (!monitor)
     return;
 
   PowerMonitorSource* source = monitor->Source();
 
   // Suppress duplicate notifications.  Some platforms may
   // send multiple notifications of the same event.
   switch (event_id) {
     case POWER_STATE_EVENT:
       {
@@ skipping 21 matching lines @@
     case SUSPEND_EVENT:
       if (!source->suspended_) {
         source->suspended_ = true;
         monitor->NotifySuspend();
       }
       break;
   }
 }
 
 }  // namespace base