Make the SystemMonitor observer list thread safe....

base/system_monitor_win.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"
 
 namespace base {
 
 void SystemMonitor::ProcessWmPowerBroadcastMessage(int event_id) {
   PowerEvent power_event;
   switch (event_id) {
     case PBT_APMPOWERSTATUSCHANGE:
-      power_event = PowerStateEvent;
+      power_event = POWER_STATE_EVENT;
       break;
     case PBT_APMRESUMEAUTOMATIC:
-      power_event = ResumeEvent;
+      power_event = RESUME_EVENT;
       break;
     case PBT_APMSUSPEND:
-      power_event = SuspendEvent;
+      power_event = SUSPEND_EVENT;
       break;
     default:
       DCHECK(false);
   }
   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
+} // namespace base