[CrOS Tether]: Add LocalDeviceDataProvider, which fetches device data for the local device.

chromeos/components/tether/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.
 
 assert(is_chromeos, "Non-ChromeOS builds cannot depend on //chromeos")
 
 static_library("tether") {
   sources = [
     "host_scan_scheduler.cc",
     "host_scan_scheduler.h",
     "host_scanner.cc",
     "host_scanner.h",
     "initializer.cc",
     "initializer.h",
+    "local_device_data_provider.cc",
+    "local_device_data_provider.h",
   ]
 
   deps = [
     "//base",
     "//chromeos",
     "//components/cryptauth",
     "//components/proximity_auth/logging",
   ]
 
   public_deps = [
@@ skipping 14 matching lines @@
     "//base",
     "//testing/gmock",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
 
   sources = [
     "host_scan_scheduler_unittest.cc",
+    "local_device_data_provider_unittest.cc",
   ]
 
   deps = [
     ":test_support",
     ":tether",
     "//base/test:test_support",
     "//chromeos",
     "//components/cryptauth",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }