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

device/generic_sensor/platform_sensor_provider_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_PUBLIC_PLATFORM_SENSOR_PROVIDER_LINUX_H_
-#define DEVICE_GENERIC_SENSOR_PUBLIC_PLATFORM_SENSOR_PROVIDER_LINUX_H_
-
-#include "device/generic_sensor/platform_sensor_provider.h"
-
-namespace base {
-class Thread;
-}
-
-namespace device {
-
-struct SensorDataLinux;
-class SensorReader;
-
-class PlatformSensorProviderLinux : public PlatformSensorProvider {
- public:
-  PlatformSensorProviderLinux();
-  ~PlatformSensorProviderLinux() override;
-
-  static PlatformSensorProviderLinux* GetInstance();
-
- protected:
-  void CreateSensorInternal(mojom::SensorType type,
-                            mojo::ScopedSharedBufferMapping mapping,
-                            const CreateSensorCallback& callback) override;
-
-  void AllSensorsRemoved() override;
-
-  void SetFileTaskRunner(
-      scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) override;
-
- private:
-  void SensorReaderFound(
-      mojom::SensorType type,
-      mojo::ScopedSharedBufferMapping mapping,
-      const PlatformSensorProviderBase::CreateSensorCallback& callback,
-      const SensorDataLinux& data,
-      std::unique_ptr<SensorReader> sensor_reader);
-
-  // Stops a polling thread if there are no sensors left. Must be called on
-  // a different that polling thread that allows io.
-  void StopPollingThread();
-
-  // TODO(maksims): make a separate class Manager that will
-  // create provide sensors with a polling task runner, check sensors existence
-  // and notify provider if a new sensor has appeared and it can be created if a
-  // request comes again for the same sensor.
-  // A use case example: a request for a sensor X comes, manager checks if the
-  // sensor exists on a platform and notifies a provider it is not found.
-  // The provider stores this information into its cache and doesn't try to
-  // create this specific sensor if a request comes. But when, for example,
-  // the sensor X is plugged into a usb port, the manager notices that and
-  // notifies the provider, which updates its cache and starts handling requests
-  // for the sensor X.
-  //
-  // Right now, this thread is used to find sensors files and poll data.
-  std::unique_ptr<base::Thread> polling_thread_;
-
-  // A task runner that is passed to polling sensors to poll data.
-  scoped_refptr<base::SingleThreadTaskRunner> polling_thread_task_runner_;
-
-  // Browser's file thread task runner passed from renderer. Used to
-  // stop a polling thread.
-  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
-
-  DISALLOW_COPY_AND_ASSIGN(PlatformSensorProviderLinux);
-};
-
-}  // namespace device
-
-#endif  // DEVICE_GENERIC_SENSOR_PUBLIC_PLATFORM_SENSOR_PROVIDER_LINUX_H_