A new copy of the old system monitor changelist.

base/system_monitor.h

 // 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.
 
 #ifndef BASE_SYSTEM_MONITOR_H_
 #define BASE_SYSTEM_MONITOR_H_
 
 #include "base/observer_list_threadsafe.h"
 #include "base/singleton.h"
 
 namespace base {
 
 // Class for monitoring various system-related subsystems
 // such as power management, network status, etc.
 // TODO(mbelshe):  Add support beyond just power management.
 class SystemMonitor {
  public:
   // Access to the Singleton
   static SystemMonitor* Get() {
     return Singleton<SystemMonitor>::get();
   }
 
-  // To start the System Monitor within an application
-  // use this call.
+  // Start the System Monitor within a process.  This method
+  // is provided so tht the battery check can be deferred.
+  // The MessageLoop must be started before calling this
+  // method.
   static void Start();
 
   //
   // Power-related APIs
   //
 
   // Is the computer currently on battery power.
   // Can be called on any thread.
   bool BatteryPower() { 
     // Using a lock here is not necessary for just a bool.
@@ skipping 70 matching lines @@
 
   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };
 
 }
 
 #endif  // BASE_SYSTEM_MONITOR_H_