Create a FakeTetherService, which stubs out TetherService for development.

chrome/browser/chromeos/BUILD.gn

 # Copyright 2014 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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//printing/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
@@ skipping 1346 matching lines @@
     "system_logs/debug_log_writer.h",
     "system_logs/device_event_log_source.cc",
     "system_logs/device_event_log_source.h",
     "system_logs/lsb_release_log_source.cc",
     "system_logs/lsb_release_log_source.h",
     "system_logs/single_log_source.cc",
     "system_logs/single_log_source.h",
     "system_logs/touch_log_source.h",
     "system_logs/touch_log_source_ozone.cc",
     "system_logs/touch_log_source_x11.cc",
+    "tether/fake_tether_service.cc",
+    "tether/fake_tether_service.h",
     "tether/tether_service.cc",
     "tether/tether_service.h",
     "tether/tether_service_factory.cc",
     "tether/tether_service_factory.h",
     "ui/accessibility_cursor_ring_layer.cc",
     "ui/accessibility_cursor_ring_layer.h",
     "ui/accessibility_focus_ring.cc",
     "ui/accessibility_focus_ring.h",
     "ui/accessibility_focus_ring_controller.cc",
     "ui/accessibility_focus_ring_controller.h",
@@ skipping 488 matching lines @@
     "policy/proto/chrome_device_policy.proto",
     "policy/proto/install_attributes.proto",
   ]
 }
 
 proto_library("attestation_proto") {
   sources = [
     "attestation/attestation_key_payload.proto",
   ]
 }