Add RELATIVE_ORIENTATION sensor implementation on macOS to //device/generic_sensor

device/generic_sensor/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.
 
 component("cpp") {
   sources = [
     "platform_sensor_configuration.cc",
     "platform_sensor_configuration.h",
     "sensor_reading.cc",
     "sensor_reading.h",
+    "sensor_shared_buffer_reader.cc",
+    "sensor_shared_buffer_reader.h",
   ]
 
   defines = [ "DEVICE_GENERIC_SENSOR_PUBLIC_IMPLEMENTATION" ]
 
   public_deps = [
     "//device/generic_sensor/public/interfaces",
   ]
 
   deps = [
     "//base",
     "//device/base/synchronization",
   ]
 }