Make base::PowerMonitor work on Chrome OS.

base/power_monitor/power_monitor_device_source_chromeos.cc

+// Copyright 2014 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"
+#include "base/power_monitor/power_monitor_device_source.h"
+#include "base/power_monitor/power_monitor_source.h"
+
+namespace base {
+
+namespace {
+
+// The most-recently-seen power source.
+bool g_on_battery = false;
+
+}  // namespace
+
+// static
+void PowerMonitorDeviceSource::SetPowerSource(bool on_battery) {
+  if (on_battery != g_on_battery) {
+    g_on_battery = on_battery;
+    ProcessPowerEvent(POWER_STATE_EVENT);
+  }
+}
+
+// static
+void PowerMonitorDeviceSource::HandleSystemSuspending() {
+  ProcessPowerEvent(SUSPEND_EVENT);
+}
+
+// static
+void PowerMonitorDeviceSource::HandleSystemResumed() {
+  ProcessPowerEvent(RESUME_EVENT);
+}
+
+bool PowerMonitorDeviceSource::IsOnBatteryPowerImpl() {
+  return g_on_battery;
+}
+
+}  // namespace base