[sensors](CrOS/Linux) Implement Sensor device manager for sensors

device/generic_sensor/linux/sensor_data_linux.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_LINUX_SENSOR_DATA_LINUX_H_
 #define DEVICE_GENERIC_SENSOR_LINUX_SENSOR_DATA_LINUX_H_
 
 #include "device/generic_sensor/generic_sensor_export.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom.h"
 
 namespace device {
 
+class PlatformSensorConfiguration;
 struct SensorReading;
 
-// This structure represents a context that is used to
-// create a type specific SensorReader and a concrete
-// sensor that uses the SensorReader to read sensor
-// data from files specified in the |sensor_file_names|.
-struct DEVICE_GENERIC_SENSOR_EXPORT SensorDataLinux {
-  using ReaderFunctor =
-      base::Callback<void(double scaling, SensorReading& reading)>;
+// This structure represents a context that is used to identify a udev device
+// and create a type specific SensorInfoLinux. For example, when a
+// SensorDeviceManager receives a udev device, it uses this structure to
+// identify what type of sensor that is and creates a SensorInfoLinux structure
+// that holds all the necessary information to create a PlatformSensorLinux.
+struct DEVICE_GENERIC_SENSOR_EXPORT SensorPathsLinux {
+  using ReaderFunctor = base::Callback<
+      void(double scaling, double offset, SensorReading& reading)>;
 
-  SensorDataLinux();
-  ~SensorDataLinux();
-  SensorDataLinux(const SensorDataLinux& other);
+  SensorPathsLinux();
+  ~SensorPathsLinux();
+  SensorPathsLinux(const SensorPathsLinux& other);
   // Provides a base path to all sensors.
   const base::FilePath::CharType* base_path_sensor_linux;
   // Provides an array of sensor file names to be searched for.
   // Different sensors might have up to 3 different file name arrays.
   // One file must be found from each array.
   std::vector<std::vector<std::string>> sensor_file_names;
   // Scaling file to be found.
   std::string sensor_scale_name;
+  // Frequency file to be found.
+  std::string sensor_frequency_file_name;
+  // Offset file to be found.
+  std::string sensor_offset_file_name;
   // Used to apply scalings to raw sensor data.
   ReaderFunctor apply_scaling_func;
-  // Reporting mode of a sensor.
-  mojom::ReportingMode reporting_mode;
+  // Sensor type
+  mojom::SensorType type;
   // Default configuration of a sensor.
   PlatformSensorConfiguration default_configuration;
 };
 
-// Initializes a sensor type specific data.
-bool InitSensorData(mojom::SensorType type, SensorDataLinux* data);
+// Initializes sensor data according to |type|.
+bool DEVICE_GENERIC_SENSOR_EXPORT InitSensorData(mojom::SensorType type,
+                                                 SensorPathsLinux* data);
+
+// This structure represents an iio device, which info is taken
+// from udev service. If a client requests a sensor from a provider,
+// the provider takes this initialized and stored structure and uses it to
+// create a requested PlatformSensorLinux of a certain type.
+struct SensorInfoLinux {
+  // Represents current sensor device node.
+  const std::string device_node;
+  // Represents frequency of a sensor.
+  const double device_frequency;
+  // Represents scaling value to be applied on raw data.
+  const double device_scaling_value;
+  // Represents offset value that must be applied on raw data.
+  const double device_offset_value;
+  // Reporting mode of a sensor taken from SensorDataLinux.
+  const mojom::ReportingMode reporting_mode;
+  // Functor that is used to convert raw data.
+  const SensorPathsLinux::ReaderFunctor apply_scaling_func;
+  // Sensor files in sysfs. Used to poll data.
+  const std::vector<base::FilePath> device_reading_files;
+
+  SensorInfoLinux(const std::string& sensor_device_node,
+                  double sensor_device_frequency,
+                  double sensor_device_scaling_value,
+                  double sensor_device_offset_value,
+                  mojom::ReportingMode mode,
+                  SensorPathsLinux::ReaderFunctor scaling_func,
+                  std::vector<base::FilePath> iio_device_reading_files);
+  ~SensorInfoLinux();
+};
 
 }  // namespace device
 
 #endif  // DEVICE_GENERIC_SENSOR_LINUX_SENSOR_DATA_LINUX_H_