Fix and refactor downloaded file handling in the loading stack

content/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/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
 import("//third_party/WebKit/public/public_features.gni")
@@ skipping 735 matching lines @@
     "leveldb_wrapper_impl.cc",
     "leveldb_wrapper_impl.h",
     "loader/async_resource_handler.cc",
     "loader/async_resource_handler.h",
     "loader/async_revalidation_driver.cc",
     "loader/async_revalidation_driver.h",
     "loader/async_revalidation_manager.cc",
     "loader/async_revalidation_manager.h",
     "loader/detachable_resource_handler.cc",
     "loader/detachable_resource_handler.h",
+    "loader/downloaded_temp_file_impl.cc",
+    "loader/downloaded_temp_file_impl.h",
     "loader/global_routing_id.h",
     "loader/intercepting_resource_handler.cc",
     "loader/intercepting_resource_handler.h",
     "loader/layered_resource_handler.cc",
     "loader/layered_resource_handler.h",
     "loader/loader_delegate.h",
     "loader/loader_io_thread_notifier.cc",
     "loader/loader_io_thread_notifier.h",
     "loader/mime_sniffing_resource_handler.cc",
     "loader/mime_sniffing_resource_handler.h",
@@ skipping 1212 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }