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

device/generic_sensor/platform_sensor_ambient_light_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/platform_sensor_ambient_light_iio.h"
+
+#include "base/bind.h"
+#include "device/generic_sensor/public/cpp/device_sensors_consts.h"
+
+namespace device {
+
+PlatformSensorAmbientLightIio::PlatformSensorAmbientLightIio(
+    mojom::SensorType type,
+    mojo::ScopedSharedBufferMapping mapping,
+    PlatformSensorProvider* provider,
+    scoped_refptr<base::SingleThreadTaskRunner> polling_task_runner,
+    std::unique_ptr<SensorReader> sensor_reader)
+    : PlatformSensorIio(type,
+                        std::move(mapping),
+                        provider,
+                        std::move(polling_task_runner)),
+      lux_value_(0.0),
+      sensor_reader_(std::move(sensor_reader)),
+      weak_factory_(this) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(sensor_reader_);
+  DCHECK_EQ(type, sensor_reader_->type());
+}
+
+PlatformSensorAmbientLightIio::~PlatformSensorAmbientLightIio() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+}
+
+mojom::ReportingMode PlatformSensorAmbientLightIio::GetReportingMode() {
+  return mojom::ReportingMode::ON_CHANGE;
+}
+
+PlatformSensorConfiguration
+PlatformSensorAmbientLightIio::GetDefaultConfiguration() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  return PlatformSensorConfiguration(kDefaultAmbientLightFrequencyHz);
+}
+
+void PlatformSensorAmbientLightIio::UpdateReading() {
+  DCHECK(polling_thread_task_runner_->BelongsToCurrentThread());
+
+  double update = -1;
+  if (!sensor_reader_->ReadSensorValue(&update)) {
+    OnSensorReadFailed();
+    return;
+  }
+
+  if (lux_value_ == update) {
+    return;
+  }
+  lux_value_ = update;
+
+  SensorReading reading;
+  reading.timestamp = (base::TimeTicks::Now() - base::TimeTicks()).InSecondsF();
+  reading.values[0] = lux_value_;
+
+  bool needNotify = (GetReportingMode() == mojom::ReportingMode::ON_CHANGE);
+  UpdateSensorReading(reading, needNotify);
+}
+
+}  // namespace device