[DeviceService] Expose battery monitoring solely via the Device Service

device/battery/battery_status_service.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_service.h"
-
-#include <utility>
-
-#include "base/bind.h"
-#include "base/location.h"
-#include "base/single_thread_task_runner.h"
-#include "base/threading/thread_task_runner_handle.h"
-#include "device/battery/battery_monitor_impl.h"
-#include "device/battery/battery_status_manager.h"
-
-namespace device {
-
-BatteryStatusService::BatteryStatusService()
-    : main_thread_task_runner_(base::ThreadTaskRunnerHandle::Get()),
-      update_callback_(base::Bind(&BatteryStatusService::NotifyConsumers,
-                                  base::Unretained(this))),
-      status_updated_(false),
-      is_shutdown_(false) {
-  callback_list_.set_removal_callback(
-      base::Bind(&BatteryStatusService::ConsumersChanged,
-                 base::Unretained(this)));
-}
-
-BatteryStatusService::~BatteryStatusService() {
-}
-
-BatteryStatusService* BatteryStatusService::GetInstance() {
-  return base::Singleton<
-      BatteryStatusService,
-      base::LeakySingletonTraits<BatteryStatusService>>::get();
-}
-
-std::unique_ptr<BatteryStatusService::BatteryUpdateSubscription>
-BatteryStatusService::AddCallback(const BatteryUpdateCallback& callback) {
-  DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
-  DCHECK(!is_shutdown_);
-
-  if (!battery_fetcher_)
-    battery_fetcher_ = BatteryStatusManager::Create(update_callback_);
-
-  if (callback_list_.empty()) {
-    bool success = battery_fetcher_->StartListeningBatteryChange();
-    // On failure pass the default values back.
-    if (!success)
-      callback.Run(mojom::BatteryStatus());
-  }
-
-  if (status_updated_) {
-    // Send recent status to the new callback if already available.
-    callback.Run(status_);
-  }
-
-  return callback_list_.Add(callback);
-}
-
-void BatteryStatusService::ConsumersChanged() {
-  if (is_shutdown_)
-    return;
-
-  if (callback_list_.empty()) {
-    battery_fetcher_->StopListeningBatteryChange();
-    status_updated_ = false;
-  }
-}
-
-void BatteryStatusService::NotifyConsumers(const mojom::BatteryStatus& status) {
-  DCHECK(!is_shutdown_);
-
-  main_thread_task_runner_->PostTask(FROM_HERE, base::Bind(
-      &BatteryStatusService::NotifyConsumersOnMainThread,
-      base::Unretained(this),
-      status));
-}
-
-void BatteryStatusService::NotifyConsumersOnMainThread(
-    const mojom::BatteryStatus& status) {
-  DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
-  if (callback_list_.empty())
-    return;
-
-  status_ = status;
-  status_updated_ = true;
-  callback_list_.Notify(status_);
-}
-
-void BatteryStatusService::Shutdown() {
-  if (!callback_list_.empty())
-    battery_fetcher_->StopListeningBatteryChange();
-  battery_fetcher_.reset();
-  is_shutdown_ = true;
-}
-
-const BatteryStatusService::BatteryUpdateCallback&
-BatteryStatusService::GetUpdateCallbackForTesting() const {
-  return update_callback_;
-}
-
-void BatteryStatusService::SetBatteryManagerForTesting(
-    std::unique_ptr<BatteryStatusManager> test_battery_manager) {
-  battery_fetcher_ = std::move(test_battery_manager);
-  status_ = mojom::BatteryStatus();
-  status_updated_ = false;
-  is_shutdown_ = false;
-  main_thread_task_runner_ = base::ThreadTaskRunnerHandle::Get();
-}
-
-}  // namespace device