Split Android-specific dependency from BackgroundLoaderOffliner. Create a subfolder of c/b/offline_…

components/offline_pages/core/background/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.
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 static_library("background_offliner") {
   sources = [
     "add_request_task.cc",
     "add_request_task.h",
     "change_requests_state_task.cc",
     "change_requests_state_task.h",
     "cleanup_task.cc",
     "cleanup_task.h",
     "cleanup_task_factory.cc",
     "cleanup_task_factory.h",
     "connection_notifier.cc",
     "connection_notifier.h",
     "device_conditions.h",
     "get_requests_task.cc",
     "get_requests_task.h",
     "initialize_store_task.cc",
     "initialize_store_task.h",
+    "load_termination_listener.h",
     "mark_attempt_aborted_task.cc",
     "mark_attempt_aborted_task.h",
     "mark_attempt_completed_task.cc",
     "mark_attempt_completed_task.h",
     "mark_attempt_started_task.cc",
     "mark_attempt_started_task.h",
     "offliner.h",
     "offliner_policy.h",
     "offliner_policy_utils.cc",
     "offliner_policy_utils.h",
@@ skipping 80 matching lines @@
     ":test_support",
     "//base",
     "//base/test:test_support",
     "//components/offline_pages/core",
     "//components/offline_pages/core:switches",
     "//sql:sql",
     "//testing/gtest",
     "//url",
   ]
 }