[sensors] Ambient light sensor implementation for ChromeOS and Linux.

device/generic_sensor/platform_sensor_iio.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_GENERIC_SENSOR_PLATFORM_SENSOR_IIO_H_
+#define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_IIO_H_
+
+#include "device/generic_sensor/platform_sensor.h"
+
+#include "base/threading/thread.h"
+#include "base/timer/timer.h"
+#include "device/generic_sensor/iio/platform_sensor_utils_iio.h"
+#include "device/generic_sensor/iio/sensor_data_iio.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace device {
+
+class PlatformSensorIio : public PlatformSensor {
+ public:
+  PlatformSensorIio(mojom::SensorType type,
+                    mojo::ScopedSharedBufferMapping mapping,
+                    PlatformSensorProvider* provider,
+                    const SensorDataIio& data,
+                    std::unique_ptr<base::Thread> polling_thread,
+                    std::unique_ptr<SensorReader> sensor_reader);
+
+  mojom::ReportingMode GetReportingMode() override;
+
+ protected:
+  ~PlatformSensorIio() override;
+  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
+  void StopSensor() override;
+  bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) override;
+  PlatformSensorConfiguration GetDefaultConfiguration() override;
+
+ private:
+  void BeginPoll(const PlatformSensorConfiguration& configuration);
+  void StopPoll();
+
+  // Triggers |sensor_reader_| to read new sensor data.
+  // If new data is read, UpdateSensorReading() is called.
+  void PollForReadingData();
+
+  // Owned timer to be deleted on a polling thread.
+  base::RepeatingTimer* timer_;
+
+  const PlatformSensorConfiguration default_configuration_;
+  const mojom::ReportingMode reporting_mode_;
+
+  // A sensor reader that reads values from sensor files
+  // and stores them to a SensorReading structure.
+  std::unique_ptr<SensorReader> sensor_reader_;
+
+  // A thread that is used to poll sensor data.
+  std::unique_ptr<base::Thread> polling_thread_;
+  scoped_refptr<base::SingleThreadTaskRunner> polling_thread_task_runner_;
+
+  // Stores previously read values that are used to
+  // determine whether the recent values are changed
+  // and IPC can be notified that updates are available.
+  SensorReading old_values_;
+
+  base::WeakPtrFactory<PlatformSensorIio> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorIio);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_IIO_H_