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

device/generic_sensor/iio/platform_sensor_utils_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_IIO_PLATFORM_SENSOR_UTILS_IIO_H_
+#define DEVICE_GENERIC_SENSOR_IIO_PLATFORM_SENSOR_UTILS_IIO_H_
+
+#include "base/files/file_path.h"
+#include "device/generic_sensor/iio/sensor_data_iio.h"
+#include "device/generic_sensor/public/cpp/sensor_reading.h"
+
+namespace device {
+
+// Generic reader class that reads sensors data from
+// sensors files located in the base iio folder.
+class SensorReader {

[Mikhail, 2016/10/17 10:34:11]

needs unit tests 

[darktears, 2016/10/17 20:35:29]

Potentially tricky. Not all ChromeOS have the aforementioned files so depending
what runs on the infra it may or may not actually test/work. Some ChromeOS do
not have ambient light sensors so /sys/bus/iio is empty or nonexistent.

[maksims (do not use this acc), 2016/10/18 06:50:41]

There is no problem at all. It's possible to create temp folder with temp files,
fill some data and read from them.

[maksims (do not use this acc), 2016/10/18 06:50:41]

Got it!

+ public:
+  ~SensorReader();
+
+  // Creates a new instance of SensorReader if sensor read files
+  // has been found and |sensor_paths_| are set.
+  static std::unique_ptr<SensorReader> Create(const SensorDataIio& data);
+
+  // Reads sensor values into |*reading| from sensor files
+  // specified in |sensor_paths_|.
+  bool ReadSensorReading(SensorReading* reading);
+
+ private:
+  explicit SensorReader(std::vector<base::FilePath> sensor_paths);
+
+  // Contains paths to sensor files that are set when
+  // Create() is called.
+  const std::vector<base::FilePath> sensor_paths_;
+
+  DISALLOW_COPY_AND_ASSIGN(SensorReader);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_IIO_PLATFORM_SENSOR_UTILS_IIO_H_