Introduce lock screen app manager

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 951 matching lines @@
     "fileapi/file_access_permissions_unittest.cc",
     "fileapi/file_system_backend_unittest.cc",
     "hats/hats_finch_helper_unittest.cc",
     "hats/hats_notification_controller_unittest.cc",
     "input_method/browser_state_monitor_unittest.cc",
     "input_method/input_method_configuration_unittest.cc",
     "input_method/input_method_engine_unittest.cc",
     "input_method/input_method_manager_impl_unittest.cc",
     "input_method/input_method_persistence_unittest.cc",
     "locale_change_guard_unittest.cc",
+    "lock_screen_apps/app_manager_impl_unittest.cc",
     "lock_screen_apps/state_controller_unittest.cc",
     "login/auth/cryptohome_authenticator_unittest.cc",
     "login/easy_unlock/easy_unlock_challenge_wrapper_unittest.cc",
     "login/easy_unlock/easy_unlock_tpm_key_manager_unittest.cc",
     "login/enrollment/enrollment_screen_unittest.cc",
     "login/error_screens_histogram_helper_unittest.cc",
     "login/existing_user_controller_auto_login_unittest.cc",
     "login/hwid_checker_unittest.cc",
     "login/profile_auth_data_unittest.cc",
     "login/quick_unlock/fingerprint_storage_unittest.cc",
@@ skipping 175 matching lines @@
     "policy/proto/chrome_device_policy.proto",
     "policy/proto/install_attributes.proto",
   ]
 }
 
 proto_library("attestation_proto") {
   sources = [
     "attestation/attestation_key_payload.proto",
   ]
 }