[BackgroundSync Cleanup] Remove power observer

content/browser/background_sync/background_sync_power_observer.cc

-// Copyright 2015 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 "content/browser/background_sync/background_sync_power_observer.h"
-
-#include "base/power_monitor/power_monitor.h"
-#include "base/thread_task_runner_handle.h"
-
-namespace content {
-
-BackgroundSyncPowerObserver::BackgroundSyncPowerObserver(
-    const base::Closure& power_callback)
-    : observing_power_monitor_(false),
-      on_battery_(true),
-      power_changed_callback_(power_callback) {
-  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
-  if (power_monitor) {
-    observing_power_monitor_ = true;
-    on_battery_ = power_monitor->IsOnBatteryPower();
-    power_monitor->AddObserver(this);
-  }
-}
-
-BackgroundSyncPowerObserver::~BackgroundSyncPowerObserver() {
-  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
-
-  if (power_monitor)
-    power_monitor->RemoveObserver(this);
-}
-
-bool BackgroundSyncPowerObserver::PowerSufficient(
-    SyncPowerState power_state) const {
-  DCHECK(observing_power_monitor_);
-  DCHECK(base::PowerMonitor::Get());
-
-  switch (power_state) {
-    case POWER_STATE_AUTO:
-      // TODO(jkarlin): Also check for device status, such as power saving mode
-      // or user preferences. crbug.com/482088.
-      return true;
-    case POWER_STATE_AVOID_DRAINING:
-      return !on_battery_;
-  }
-
-  NOTREACHED();
-  return false;
-}
-
-void BackgroundSyncPowerObserver::OnPowerStateChange(bool on_battery_power) {
-  DCHECK(observing_power_monitor_);
-  DCHECK(base::PowerMonitor::Get());
-
-  if (on_battery_ == on_battery_power)
-    return;
-
-  on_battery_ = on_battery_power;
-  base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
-                                                power_changed_callback_);
-}
-
-}  // namespace content