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

device/generic_sensor/platform_sensor_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_iio.h>
+#include "base/message_loop/message_loop.h"
+
+namespace device {
+
+PlatformSensorIio::PlatformSensorIio(

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

pls add thread checks to methods

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

pls add thread check to methods

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

Done.

+    mojom::SensorType type,
+    mojo::ScopedSharedBufferMapping mapping,
+    PlatformSensorProvider* provider,
+    scoped_refptr<base::SingleThreadTaskRunner> polling_task_runner)
+    : PlatformSensor(type, std::move(mapping), provider),
+      polling_thread_task_runner_(polling_task_runner),
+      timer_(new base::RepeatingTimer()),
+      weak_factory_(this) {}
+
+PlatformSensorIio::~PlatformSensorIio() {
+  polling_thread_task_runner_->DeleteSoon(FROM_HERE, timer_);
+}
+
+bool PlatformSensorIio::StartSensor(
+    const PlatformSensorConfiguration& configuration) {
+  return polling_thread_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&PlatformSensorIio::BeginPoll,
+                            weak_factory_.GetWeakPtr(), configuration));
+}
+
+void PlatformSensorIio::BeginPoll(
+    const PlatformSensorConfiguration& configuration) {
+  DCHECK(polling_thread_task_runner_->BelongsToCurrentThread());
+  timer_->Start(FROM_HERE, base::TimeDelta::FromMicroseconds(
+                               base::Time::kMicrosecondsPerSecond /
+                               configuration.frequency()),
+                this, &PlatformSensorIio::UpdateReading);
+}
+
+void PlatformSensorIio::StopSensor() {
+  polling_thread_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&PlatformSensorIio::StopPoll, this));
+}
+
+void PlatformSensorIio::StopPoll() {
+  timer_->Stop();
+}
+
+void PlatformSensorIio::OnSensorReadFailed() {
+  StopSensor();

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

is it called on polling thread? if so, than just call StopPoll()

+  task_runner_->PostTask(FROM_HERE,
+                         base::Bind(&PlatformSensorIio::NotifySensorError,
+                                    weak_factory_.GetWeakPtr()));
+}
+
+bool PlatformSensorIio::CheckSensorConfiguration(
+    const PlatformSensorConfiguration& configuration) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  return configuration.frequency() > 0 &&
+         configuration.frequency() <=
+             mojom::SensorConfiguration::kMaxAllowedFrequency;
+}
+
+}  // namespace device