Move //device/generic_sensor to be part of the internal implementation of the Device Service.

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