Introduce lock screen app manager interface

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 693 matching lines @@
     "language_preferences.cc",
     "language_preferences.h",
     "launcher_search_provider/error_reporter.cc",
     "launcher_search_provider/error_reporter.h",
     "launcher_search_provider/launcher_search_provider_service.cc",
     "launcher_search_provider/launcher_search_provider_service.h",
     "launcher_search_provider/launcher_search_provider_service_factory.cc",
     "launcher_search_provider/launcher_search_provider_service_factory.h",
     "locale_change_guard.cc",
     "locale_change_guard.h",
+    "lock_screen_apps/app_manager.h",
+    "lock_screen_apps/app_manager_impl.cc",
+    "lock_screen_apps/app_manager_impl.h",
     "lock_screen_apps/state_controller.cc",
     "lock_screen_apps/state_controller.h",
     "lock_screen_apps/state_observer.h",
     "logging.cc",
     "logging.h",
     "login/app_launch_controller.cc",
     "login/app_launch_controller.h",
     "login/app_launch_signin_screen.cc",
     "login/app_launch_signin_screen.h",
     "login/arc_kiosk_controller.cc",
@@ skipping 1159 matching lines @@
     "policy/proto/chrome_device_policy.proto",
     "policy/proto/install_attributes.proto",
   ]
 }
 
 proto_library("attestation_proto") {
   sources = [
     "attestation/attestation_key_payload.proto",
   ]
 }