Remove DeviceLightEvent implementation

device/sensors/public/cpp/device_light_data.h

-// Copyright 2014 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_SENSORS_PUBLIC_CPP_DEVICE_LIGHT_DATA_H_
-#define DEVICE_SENSORS_PUBLIC_CPP_DEVICE_LIGHT_DATA_H_
-
-namespace device {
-
-// This struct is intentionally POD and fixed size so that it can be stored
-// in shared memory between the sensor interface impl and its clients.
-// POD class should be a struct, should have an inline cstor that uses
-// initializer lists and no dstor.
-struct DeviceLightData {
-  DeviceLightData() : value(-1) {}
-  double value;
-};
-
-}  // namespace device
-
-#endif  // DEVICE_SENSORS_PUBLIC_CPP_DEVICE_LIGHT_DATA_H_