[sensors] [mac] Implement ambient light sensor for macOS

device/generic_sensor/platform_sensor_mac.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_PLATFORM_SENSOR_MAC_H_
+#define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_MAC_H_
+
+#include "device/generic_sensor/platform_sensor.h"
+
+namespace device {
+
+class PlatformSensorMac : public PlatformSensor {
+  using PlatformSensor::PlatformSensor;
+
+ public:
+  virtual void UpdateReading() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorMac);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_MAC_H_