Battery listener for download service in native code.

components/download/internal/scheduler/battery_listener.cc

+// Copyright 2017 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 "components/download/internal/scheduler/battery_listener.h"
+
+#include "base/power_monitor/power_monitor.h"
+
+namespace download {
+
+// Helper function that converts the battery status to battery requirement.
+SchedulingParams::BatteryRequirements ToBatteryRequirement(
+    bool on_battery_power) {
+  return on_battery_power
+             ? SchedulingParams::BatteryRequirements::BATTERY_INSENSITIVE
+             : SchedulingParams::BatteryRequirements::BATTERY_SENSITIVE;
+}
+
+BatteryListener::BatteryListener() = default;
+
+BatteryListener::~BatteryListener() {
+  Stop();
+}
+
+SchedulingParams::BatteryRequirements BatteryListener::CurrentBatteryStatus()
+    const {
+  return ToBatteryRequirement(base::PowerMonitor::Get()->IsOnBatteryPower());
+}
+
+void BatteryListener::Start() {
+  base::PowerMonitor* monitor = base::PowerMonitor::Get();
+  DCHECK(monitor);
+  monitor->AddObserver(this);
+}
+
+void BatteryListener::Stop() {
+  base::PowerMonitor::Get()->RemoveObserver(this);
+}
+
+void BatteryListener::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void BatteryListener::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void BatteryListener::OnPowerStateChange(bool on_battery_power) {
+  NotifyBatteryChange(ToBatteryRequirement(on_battery_power));
+}
+
+void BatteryListener::NotifyBatteryChange(
+    SchedulingParams::BatteryRequirements current_battery) {
+  for (auto& observer : observers_)
+    observer.OnBatteryChange(current_battery);
+}
+
+}  // namespace download