Revert of 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) {
-  AutoLock lock(*PowerMonitor::GetLock());
-  if (!PowerMonitor::IsInitializedLocked())
+  PowerMonitor* monitor = PowerMonitor::Get();
+  if (!monitor)
     return;
 
-  PowerMonitorSource* source = PowerMonitor::GetSource();
+  PowerMonitorSource* source = monitor->Source();
 
   // Suppress duplicate notifications.  Some platforms may
   // send multiple notifications of the same event.
   switch (event_id) {
     case POWER_STATE_EVENT:
       {
         bool new_on_battery_power = source->IsOnBatteryPowerImpl();
         bool changed = false;
 
         {
           AutoLock auto_lock(source->battery_lock_);
           if (source->on_battery_power_ != new_on_battery_power) {
               changed = true;
               source->on_battery_power_ = new_on_battery_power;
           }
         }
 
         if (changed)
-          PowerMonitor::NotifyPowerStateChange(new_on_battery_power);
+          monitor->NotifyPowerStateChange(new_on_battery_power);
       }
       break;
     case RESUME_EVENT:
       if (source->suspended_) {
         source->suspended_ = false;
-        PowerMonitor::NotifyResume();
+        monitor->NotifyResume();
       }
       break;
     case SUSPEND_EVENT:
       if (!source->suspended_) {
         source->suspended_ = true;
-        PowerMonitor::NotifySuspend();
+        monitor->NotifySuspend();
       }
       break;
   }
 }
 
 }  // namespace base