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

device/sensors/public/cpp/BUILD.gn

 # 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.
 
 source_set("cpp") {
   sources = [
     "device_light_data.h",
     "device_light_hardware_buffer.h",
     "device_motion_hardware_buffer.h",
     "device_orientation_hardware_buffer.h",
+    "device_sensors_consts.h",
+    "device_util_mac.cc",
+    "device_util_mac.h",
   ]
 
   public_deps = [
     "//device/base/synchronization",
     "//third_party/WebKit/public:blink_headers",
   ]
 }