Disable battery power detection on POSIX since we don't currently use it.

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"
 
+// Windows HiRes timers drain the battery faster so we need to know the battery
+// status.  This isn't true for other platforms.
+#if defined(OS_WIN)
+#define ENABLE_BATTERY_MONITORING 1
+#else
+#undef ENABLE_BATTERY_MONITORING
+#endif  // !OS_WIN
+
 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() {
     // Uses the LeakySingletonTrait because cleanup is optional.
-    return 
+    return
         Singleton<SystemMonitor, LeakySingletonTraits<SystemMonitor> >::get();
   }
 
   // Start the System Monitor within a process.  This method
   // is provided so that the battery check can be deferred.
   // The MessageLoop must be started before calling this
   // method.
+  // This is a no-op on platforms for which ENABLE_BATTERY_MONITORING is
+  // disabled.
   static void Start();
 
   //
   // Power-related APIs
   //
 
   // Is the computer currently on battery power.
   // Can be called on any thread.
-  bool BatteryPower() { 
+  bool BatteryPower() {
     // Using a lock here is not necessary for just a bool.
     return battery_in_use_;
   }
 
   // Normalized list of power events.
   enum PowerEvent {
     POWER_STATE_EVENT,  // The Power status of the system has changed.
     SUSPEND_EVENT,      // The system is being suspended.
     RESUME_EVENT        // The system is being resumed.
   };
@@ skipping 29 matching lines @@
 #if defined(OS_WIN)
   // Windows-specific handling of a WM_POWERBROADCAST message.
   // Embedders of this API should hook their top-level window
   // message loop and forward WM_POWERBROADCAST through this call.
   void ProcessWmPowerBroadcastMessage(int event_id);
 #endif
 
   // Cross-platform handling of a power event.
   void ProcessPowerMessage(PowerEvent event_id);
 
-  // Constructor.  
+  // Constructor.
   // Don't use this; access SystemMonitor via the Singleton.
   SystemMonitor();
 
  private:
   // Platform-specific method to check whether the system is currently
   // running on battery power.  Returns true if running on batteries,
   // false otherwise.
   bool IsBatteryPower();
 
   // Checks the battery status and notifies observers if the battery
   // status has changed.
   void BatteryCheck();
 
   // Functions to trigger notifications.
   void NotifyPowerStateChange();
   void NotifySuspend();
   void NotifyResume();
 
   scoped_refptr<ObserverListThreadSafe<PowerObserver> > observer_list_;
   bool battery_in_use_;
   bool suspended_;
 
+#if defined(ENABLE_BATTERY_MONITORING)
   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };
 
 }
 
 #endif  // BASE_SYSTEM_MONITOR_H_