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

device/generic_sensor/iio/sensor_data_iio.cc

+// 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.
+
+#include "device/generic_sensor/iio/sensor_data_iio.h"
+#include "device/sensors/public/cpp/device_sensors_consts.h"
+
+namespace device {
+
+namespace {
+
+using mojom::SensorType;
+
+const base::FilePath::CharType* kSensorsBasePath =
+    FILE_PATH_LITERAL("/sys/bus/iio/devices");
+
+const std::string kAmbientLightFileNames[] = {
+    "in_illuminance0_input", "in_illuminance_input", "in_illuminance0_raw",
+    "in_illuminance_raw", "illuminance0_input"};
+
+}  // namespace
+
+SensorDataIio::SensorDataIio() : base_path_sensor_iio(kSensorsBasePath) {}
+
+SensorDataIio::~SensorDataIio() = default;
+
+SensorDataIio::SensorDataIio(const SensorDataIio& other) = default;
+
+bool InitSensorData(SensorType type, SensorDataIio* data) {
+  DCHECK(data);
+
+  switch (type) {
+    case SensorType::AMBIENT_LIGHT: {
+      std::vector<std::string> file_names(
+          kAmbientLightFileNames,
+          kAmbientLightFileNames + arraysize(kAmbientLightFileNames));
+      data->sensor_file_names.push_back(file_names);

[Reilly Grant (use Gerrit), 2016/10/31 21:18:09]

nit: use swap unless preserving any values already in sensor_file_names is
important

[maksims (do not use this acc), 2016/11/01 08:14:08]

As I said. std::vector<std::string> != std::vector<std::vector<std::string>>. It
will require a temp vector.

[Reilly Grant (use Gerrit), 2016/11/01 18:58:16]

Ah, right. You can use std::move(file_names) to avoid copying the temp vector
though which is really the effect I was looking for.

+      data->reporting_mode = mojom::ReportingMode::ON_CHANGE;
+      data->default_configuration =
+          PlatformSensorConfiguration(kDefaultAmbientLightFrequencyHz);
+      break;
+    }
+    default: {
+      NOTIMPLEMENTED();
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace device