Add the download component and initial setup

chrome/browser/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/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 305 matching lines @@
     "dom_distiller/profile_utils.cc",
     "dom_distiller/profile_utils.h",
     "dom_distiller/tab_utils.cc",
     "dom_distiller/tab_utils.h",
     "domain_reliability/service_factory.cc",
     "domain_reliability/service_factory.h",
     "doodle/doodle_service_factory.cc",
     "doodle/doodle_service_factory.h",
     "download/all_download_item_notifier.cc",
     "download/all_download_item_notifier.h",
+    "download/background_download_service_factory.cc",
+    "download/background_download_service_factory.h",
     "download/chrome_download_manager_delegate.cc",
     "download/chrome_download_manager_delegate.h",
     "download/download_confirmation_reason.h",
     "download/download_confirmation_result.h",
     "download/download_crx_util_android.cc",
     "download/download_file_picker.cc",
     "download/download_file_picker.h",
     "download/download_history.cc",
     "download/download_history.h",
     "download/download_item_model.cc",
@@ skipping 1136 matching lines @@
     "//components/crx_file",
     "//components/data_reduction_proxy/content/browser",
     "//components/data_reduction_proxy/core/browser",
     "//components/data_usage/core",
     "//components/data_use_measurement/content",
     "//components/data_use_measurement/core:ascriber",
     "//components/device_event_log",
     "//components/dom_distiller/content/browser",
     "//components/domain_reliability",
     "//components/doodle",
+    "//components/download",
     "//components/error_page/common",
     "//components/favicon/content",
     "//components/favicon/core",
     "//components/favicon_base",
     "//components/flags_ui",
     "//components/gcm_driver",
     "//components/google/core/browser",
     "//components/guest_view/browser",
     "//components/handoff",
     "//components/history/content/browser",
@@ skipping 3203 matching lines @@
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }
 
 service_manifest("preferences_forwarder_manifest") {
   name = "preferences_forwarder"
   source = "prefs/forwarder_manifest.json"
 }