[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/timer/timer.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace device {
+
+class PlatformSensorIio : public PlatformSensor {
+ public:
+  PlatformSensorIio(
+      mojom::SensorType type,
+      mojo::ScopedSharedBufferMapping mapping,
+      PlatformSensorProvider* provider,
+      scoped_refptr<base::SingleThreadTaskRunner> polling_task_runner);
+
+  virtual void UpdateReading() = 0;

[Mikhail, 2016/10/11 14:46:47]

rename to 'PollForReadingData()'. Can it be protected?

[maksims (do not use this acc), 2016/10/14 12:31:45]

Done.

+
+ protected:
+  ~PlatformSensorIio() override;
+  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
+  void StopSensor() override;
+  bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) override;
+
+  void OnSensorReadFailed();
+
+  // Task runner that is used to poll sensor data from
+  // sensor files.
+  scoped_refptr<base::SingleThreadTaskRunner> polling_thread_task_runner_;
+
+ private:
+  void BeginPoll(const PlatformSensorConfiguration& configuration);
+  void StopPoll();
+  void OnStop();
+
+  // Owned timer to be deleted on polling thread.
+  base::RepeatingTimer* timer_;
+
+  base::WeakPtrFactory<PlatformSensorIio> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorIio);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_IIO_H_