[DeviceService] Expose battery monitoring solely via the Device Service

device/battery/battery_status_manager_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 "device/battery/battery_status_manager.h"
-
-#include <memory>
-
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "chromeos/dbus/dbus_thread_manager.h"
-#include "chromeos/dbus/power_manager/power_supply_properties.pb.h"
-#include "chromeos/dbus/power_manager_client.h"
-
-namespace device {
-
-namespace {
-
-class PowerManagerObserver
-    : public chromeos::PowerManagerClient::Observer,
-      public base::RefCountedThreadSafe<PowerManagerObserver> {
- public:
-  explicit PowerManagerObserver(
-      const BatteryStatusService::BatteryUpdateCallback& callback)
-      : callback_(callback), currently_listening_(false) {}
-
-  // Starts listening for updates.
-  void Start() {
-    if (currently_listening_)
-      return;
-    chromeos::PowerManagerClient* power_client =
-        chromeos::DBusThreadManager::Get()->GetPowerManagerClient();
-    power_client->AddObserver(this);
-    power_client->RequestStatusUpdate();
-    currently_listening_ = true;
-  }
-
-  // Stops listening for updates.
-  void Stop() {
-    if (!currently_listening_)
-      return;
-    chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(
-        this);
-    currently_listening_ = false;
-  }
-
- private:
-  friend class base::RefCountedThreadSafe<PowerManagerObserver>;
-
-  ~PowerManagerObserver() override {}
-
-  bool IsBatteryPresent(
-      const power_manager::PowerSupplyProperties& proto) const {
-    return proto.battery_state() !=
-           power_manager::PowerSupplyProperties_BatteryState_NOT_PRESENT;
-  }
-
-  bool IsUsbChargerConnected(
-      const power_manager::PowerSupplyProperties& proto) const {
-    return proto.external_power() ==
-           power_manager::PowerSupplyProperties_ExternalPower_USB;
-  }
-
-  bool IsBatteryCharging(
-      const power_manager::PowerSupplyProperties& proto) const {
-    return proto.battery_state() !=
-           power_manager::PowerSupplyProperties_BatteryState_DISCHARGING;
-  }
-
-  bool IsBatteryFull(const power_manager::PowerSupplyProperties& proto) const {
-    return proto.battery_state() ==
-           power_manager::PowerSupplyProperties_BatteryState_FULL;
-  }
-
-  double GetBatteryLevel(
-      const power_manager::PowerSupplyProperties& proto) const {
-    const double kMaxBatteryLevelProto = 100.f;
-    return proto.battery_percent() / kMaxBatteryLevelProto;
-  }
-
-  // chromeos::PowerManagerClient::Observer:
-  void PowerChanged(
-      const power_manager::PowerSupplyProperties& proto) override {
-    mojom::BatteryStatus status;
-
-    // Use the default values if there is no battery in the system.
-    if (IsBatteryPresent(proto)) {
-      // The charging status is unreliable if a low power charger is connected
-      // (i.e. usb).
-      bool status_unreliable = IsUsbChargerConnected(proto);
-      // Battery time is unreliable if it is still being computed.
-      bool time_unreliable =
-          status_unreliable || proto.is_calculating_battery_time();
-
-      // Set |charging| only if the status is reliable. Otherwise, keep the
-      // default (which is |true|).
-      if (!status_unreliable)
-        status.charging = IsBatteryCharging(proto);
-
-      // Set |chargingTime| to +infinity if the battery is discharging, or if
-      // the time is unreliable. Keep the default value (which is 0) if the
-      // battery is full.
-      if (time_unreliable || !status.charging)
-        status.charging_time = std::numeric_limits<double>::infinity();
-      else if (!IsBatteryFull(proto))
-        status.charging_time = proto.battery_time_to_full_sec();
-
-      // Keep the default value for |dischargingTime| (which is +infinity) if
-      // the time is unreliable, or if the battery is charging.
-      if (!time_unreliable && !status.charging)
-        status.discharging_time = proto.battery_time_to_empty_sec();
-
-      status.level = GetBatteryLevel(proto);
-    }
-    callback_.Run(status);
-  }
-
-  BatteryStatusService::BatteryUpdateCallback callback_;
-  bool currently_listening_;
-
-  DISALLOW_COPY_AND_ASSIGN(PowerManagerObserver);
-};
-
-class BatteryStatusManagerChromeOS
-    : public BatteryStatusManager,
-      public chromeos::PowerManagerClient::Observer {
- public:
-  explicit BatteryStatusManagerChromeOS(
-      const BatteryStatusService::BatteryUpdateCallback& callback)
-      : observer_(new PowerManagerObserver(callback)) {}
-
-  ~BatteryStatusManagerChromeOS() override { observer_->Stop(); }
-
- private:
-  // BatteryStatusManager:
-  bool StartListeningBatteryChange() override {
-    observer_->Start();
-    return true;
-  }
-
-  void StopListeningBatteryChange() override { observer_->Stop(); }
-
-  scoped_refptr<PowerManagerObserver> observer_;
-
-  DISALLOW_COPY_AND_ASSIGN(BatteryStatusManagerChromeOS);
-};
-
-}  // namespace
-
-// static
-std::unique_ptr<BatteryStatusManager> BatteryStatusManager::Create(
-    const BatteryStatusService::BatteryUpdateCallback& callback) {
-  return std::unique_ptr<BatteryStatusManager>(
-      new BatteryStatusManagerChromeOS(callback));
-}
-
-}  // namespace device