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

device/generic_sensor/platform_sensor_provider_linux.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_provider_linux.h"
-
-#include "base/memory/singleton.h"
-#include "base/task_runner_util.h"
-#include "base/threading/thread.h"
-#include "device/generic_sensor/linux/platform_sensor_utils_linux.h"
-#include "device/generic_sensor/linux/sensor_data_linux.h"
-#include "device/generic_sensor/platform_sensor_linux.h"
-
-namespace device {
-
-// static
-PlatformSensorProviderLinux* PlatformSensorProviderLinux::GetInstance() {
-  return base::Singleton<
-      PlatformSensorProviderLinux,
-      base::LeakySingletonTraits<PlatformSensorProviderLinux>>::get();
-}
-
-PlatformSensorProviderLinux::PlatformSensorProviderLinux() = default;
-
-PlatformSensorProviderLinux::~PlatformSensorProviderLinux() = default;
-
-void PlatformSensorProviderLinux::CreateSensorInternal(
-    mojom::SensorType type,
-    mojo::ScopedSharedBufferMapping mapping,
-    const CreateSensorCallback& callback) {
-  SensorDataLinux data;
-  if (!InitSensorData(type, &data)) {
-    callback.Run(nullptr);
-    return;
-  }
-
-  if (!polling_thread_)
-    polling_thread_.reset(new base::Thread("Sensor polling thread"));
-
-  if (!polling_thread_->IsRunning()) {
-    if (!polling_thread_->StartWithOptions(
-            base::Thread::Options(base::MessageLoop::TYPE_IO, 0))) {
-      callback.Run(nullptr);
-      return;
-    }
-    polling_thread_task_runner_ = polling_thread_->task_runner();
-  }
-
-  base::PostTaskAndReplyWithResult(
-      polling_thread_task_runner_.get(), FROM_HERE,
-      base::Bind(SensorReader::Create, data),
-      base::Bind(&PlatformSensorProviderLinux::SensorReaderFound,
-                 base::Unretained(this), type, base::Passed(&mapping), callback,
-                 data));
-}
-
-void PlatformSensorProviderLinux::SensorReaderFound(
-    mojom::SensorType type,
-    mojo::ScopedSharedBufferMapping mapping,
-    const PlatformSensorProviderBase::CreateSensorCallback& callback,
-    const SensorDataLinux& data,
-    std::unique_ptr<SensorReader> sensor_reader) {
-  DCHECK(CalledOnValidThread());
-
-  if (!sensor_reader) {
-    // If there are no sensors, stop polling thread.
-    if (!HasSensors())
-      AllSensorsRemoved();
-    callback.Run(nullptr);
-    return;
-  }
-
-  callback.Run(new PlatformSensorLinux(type, std::move(mapping), this, data,
-                                       std::move(sensor_reader),
-                                       polling_thread_task_runner_));
-}
-
-void PlatformSensorProviderLinux::SetFileTaskRunner(
-    scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) {
-  DCHECK(CalledOnValidThread());
-  if (!file_task_runner_)
-    file_task_runner_ = file_task_runner;
-}
-
-void PlatformSensorProviderLinux::AllSensorsRemoved() {
-  DCHECK(CalledOnValidThread());
-  DCHECK(file_task_runner_);
-  // When there are no sensors left, the polling thread must be stopped.
-  // Stop() can only be called on a different thread that allows io.
-  // Thus, browser's file thread is used for this purpose.
-  file_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&PlatformSensorProviderLinux::StopPollingThread,
-                            base::Unretained(this)));
-}
-
-void PlatformSensorProviderLinux::StopPollingThread() {
-  DCHECK(file_task_runner_);
-  DCHECK(file_task_runner_->BelongsToCurrentThread());
-  polling_thread_->Stop();
-}
-
-}  // namespace device