Add BASE_API to SystemMonitor::PowerObserver to be able to

base/system_monitor/system_monitor.h

 // Copyright (c) 2011 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_SYSTEM_MONITOR_H_
 #define BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_
 #pragma once
 
 #include "base/base_api.h"
 #include "base/basictypes.h"
@@ skipping 48 matching lines @@
   bool BatteryPower() const {
     // Using a lock here is not necessary for just a bool.
     return battery_in_use_;
   }
 
   // Callbacks will be called on the thread which creates the SystemMonitor.
   // During the callback, Add/RemoveObserver will block until the callbacks
   // are finished. Observers should implement quick callback functions; if
   // lengthy operations are needed, the observer should take care to invoke
   // the operation on an appropriate thread.
-  class PowerObserver {
+  class BASE_API PowerObserver {
    public:
     // Notification of a change in power status of the computer, such
     // as from switching between battery and A/C power.
     virtual void OnPowerStateChange(bool on_battery_power) {}
 
     // Notification that the system is suspending.
     virtual void OnSuspend() {}
 
     // Notification that the system is resuming.
     virtual void OnResume() {}
@@ skipping 54 matching lines @@
   IONotificationPortRef notification_port_ref_;
   io_object_t notifier_object_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };
 
 }  // namespace base
 
 #endif  // BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_