Generic Sensor API : Ambient Light Sensor API.

device/sensor/sensor_service.h

+// Copyright 2016 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.
+
+#ifndef DEVICE_SENSOR_SENSOR_SERVICE_H_
+#define DEVICE_SENSOR_SENSOR_SERVICE_H_
+
+#include "base/callback_list.h"
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+
+#include "device/sensor/als_reading.mojom.h"
+#include "device/sensor/sensor_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace device {
+class SensorManager;
+
+class DEVICE_SENSOR_EXPORT SensorService {
+ public:
+  typedef base::Callback<void(const AmbientLightSensorReading&)>
+      SensorUpdateCallback;
+  typedef base::CallbackList<void(const AmbientLightSensorReading&)>
+      SensorUpdateCallbackList;
+  typedef SensorUpdateCallbackList::Subscription SensorUpdateSubscription;
+
+  // Returns the SensorService singleton.
+  static SensorService* GetInstance();
+
+  std::unique_ptr<SensorUpdateSubscription> AddCallback(
+      const SensorUpdateCallback& callback);
+
+  void Shutdown();
+
+ private:
+  friend struct base::DefaultSingletonTraits<SensorService>;
+
+  SensorService();
+  virtual ~SensorService();
+
+  // Updates current als_reading and sends new reading to interested
+  // render processes. Can be called on any thread via a callback.
+  void NotifyConsumers(const AmbientLightSensorReading& reading);
+  void NotifyConsumersOnMainThread(const AmbientLightSensorReading& reading);
+  void ConsumersChanged();
+
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+  std::unique_ptr<SensorManager> sensor_fetcher_;
+  SensorUpdateCallbackList callback_list_;
+  SensorUpdateCallback update_callback_;
+  AmbientLightSensorReading reading_;
+  bool reading_updated_;
+  bool is_shutdown_;
+
+  DISALLOW_COPY_AND_ASSIGN(SensorService);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_SENSOR_SENSOR_SERVICE_H_