SystemMonitor refactoring: move power state monitor into a separate class called PowerMonitor

base/power_monitor/power_monitor_win.cc

+// 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.
+
+#include "base/power_monitor/power_monitor.h"
+
+namespace base {
+
+// Function to query the system to see if it is currently running on
+// battery power.  Returns true if running on battery.
+bool PowerMonitor::IsBatteryPower() {
+  SYSTEM_POWER_STATUS status;
+  if (!GetSystemPowerStatus(&status)) {
+    DLOG(ERROR) << "GetSystemPowerStatus failed: " << GetLastError();
+    return false;
+  }
+  return (status.ACLineStatus == 0);
+}
+
+}  // namespace base