[Device Service] Move PowerMonitor into the Device Service

services/device/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.
 
 import("//services/service_manager/public/cpp/service.gni")
 import("//services/service_manager/public/service_manifest.gni")
 
 source_set("lib") {
   sources = [
     "device_service.cc",
     "device_service.h",
   ]
 
   deps = [
     "//base",
+    "//device/power_monitor",
     "//services/service_manager/public/cpp",
   ]
 
   data_deps = [
     ":manifest",
   ]
 }
 
 service_manifest("manifest") {
   name = "device"
   source = "manifest.json"
 }