Revert of Move //device/generic_sensor to be part of the internal implementation of the Device Service.

device/generic_sensor/platform_sensor_provider_mac.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_mac.h"
+
+#include "base/memory/singleton.h"
+#include "device/generic_sensor/platform_sensor_accelerometer_mac.h"
+#include "device/generic_sensor/platform_sensor_ambient_light_mac.h"
+
+namespace device {
+
+// static
+PlatformSensorProviderMac* PlatformSensorProviderMac::GetInstance() {
+  return base::Singleton<
+      PlatformSensorProviderMac,
+      base::LeakySingletonTraits<PlatformSensorProviderMac>>::get();
+}
+
+PlatformSensorProviderMac::PlatformSensorProviderMac() = default;
+
+PlatformSensorProviderMac::~PlatformSensorProviderMac() = default;
+
+void PlatformSensorProviderMac::CreateSensorInternal(
+    mojom::SensorType type,
+    mojo::ScopedSharedBufferMapping mapping,
+    const CreateSensorCallback& callback) {
+  // Create Sensors here.
+  switch (type) {
+    case mojom::SensorType::AMBIENT_LIGHT: {
+      scoped_refptr<PlatformSensor> sensor =
+          new PlatformSensorAmbientLightMac(std::move(mapping), this);
+      callback.Run(std::move(sensor));
+      break;
+    }
+    case mojom::SensorType::ACCELEROMETER: {
+      callback.Run(base::MakeRefCounted<PlatformSensorAccelerometerMac>(
+          std::move(mapping), this));
+      break;
+    }
+    default:
+      NOTIMPLEMENTED();
+      callback.Run(nullptr);
+  }
+}
+
+}  // namespace device