Remove DeviceLightEvent implementation

device/sensors/device_sensor_service.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_DEVICE_SENSOR_SERVICE_H_
 #define DEVICE_SENSORS_DEVICE_SENSOR_SERVICE_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
@@ skipping 44 matching lines @@
 
  private:
   friend struct base::DefaultSingletonTraits<DeviceSensorService>;
 
   DeviceSensorService();
   ~DeviceSensorService() override;
 
   bool ChangeNumberConsumers(ConsumerType consumer_type, int delta);
   int GetNumberConsumers(ConsumerType consumer_type) const;
 
-  int num_light_readers_;
   int num_motion_readers_;
   int num_orientation_readers_;
   int num_orientation_absolute_readers_;
   bool is_shutdown_;
   std::unique_ptr<DataFetcherSharedMemory> data_fetcher_;
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceSensorService);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_SENSORS_DEVICE_SENSOR_SERVICE_H_