Remove DeviceLightEvent implementation

device/sensors/BUILD.gn

 # Copyright 2017 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.
 
 import("//build/config/features.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")  # For generate_jni().
 }
 
 component("sensors") {
   sources = [
-    "ambient_light_mac.cc",
-    "ambient_light_mac.h",
     "android/device_sensor_jni_registrar.cc",
     "android/device_sensor_jni_registrar.h",
     "data_fetcher_shared_memory.h",
     "data_fetcher_shared_memory_android.cc",
     "data_fetcher_shared_memory_base.cc",
     "data_fetcher_shared_memory_base.h",
     "data_fetcher_shared_memory_chromeos.cc",
     "data_fetcher_shared_memory_default.cc",
     "data_fetcher_shared_memory_mac.cc",
     "data_fetcher_shared_memory_win.cc",
@@ skipping 76 matching lines @@
     ]
   }
 
   java_cpp_enum("device_sensors_android_java_enums_srcjar") {
     sources = [
       "device_sensors_consts.h",
       "sensor_manager_android.h",
     ]
   }
 }