Battery Status API: browser-side implementation.

content/browser/battery_status/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 "content/browser/battery_status/battery_status_service.h"
+
+#include "base/bind.h"
+#include "content/browser/battery_status/battery_status_manager.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+BatteryStatusService::BatteryStatusService()
+    : status_updated_(false),
+      is_shutdown_(false) {
+  update_callback_ = base::Bind(&BatteryStatusService::UpdateBatteryStatus,
+                                base::Unretained(this));
+  callback_list_.set_removal_callback(
+      base::Bind(&BatteryStatusService::ConsumersChanged,
+                 base::Unretained(this)));
+}
+
+BatteryStatusService::~BatteryStatusService() {
+}
+
+BatteryStatusService* BatteryStatusService::GetInstance() {
+  return Singleton<BatteryStatusService,
+                   LeakySingletonTraits<BatteryStatusService> >::get();
+}
+
+scoped_ptr<BatteryStatusService::BatteryUpdateSubscription>
+BatteryStatusService::AddCallback(const BatteryUpdateCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(!is_shutdown_);
+
+  if (!battery_fetcher_)
+    battery_fetcher_.reset(new BatteryStatusManager(update_callback_));
+
+  if (callback_list_.empty())
+    battery_fetcher_->StartListeningBatteryChange();
+
+  if (status_updated_) {
+    // Send recent status to the new callback if already available.
+    callback.Run(status_);
+  }
+
+  return callback_list_.Add(callback);
+}
+
+void BatteryStatusService::ConsumersChanged() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(!is_shutdown_);
+
+  if (callback_list_.empty()) {
+      battery_fetcher_->StopListeningBatteryChange();
+      status_updated_ = false;
+  }
+}
+
+void BatteryStatusService::UpdateBatteryStatus(
+    const blink::WebBatteryStatus& status) {
+  DCHECK(!is_shutdown_);
+  BrowserThread::PostTask(BrowserThread::IO,
+                          FROM_HERE,
+                          base::Bind(&BatteryStatusService::NotifyConsumers,
+                                     base::Unretained(this), status));
+}
+
+void BatteryStatusService::NotifyConsumers(
+    const blink::WebBatteryStatus& status) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  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(
+    BatteryStatusManager* test_battery_manager) {
+  battery_fetcher_.reset(test_battery_manager);
+  blink::WebBatteryStatus status;
+  status_ = status;
+  status_updated_ = false;
+}
+
+}  // namespace content