Factor Chrome details out of update manifest fetching.

extensions/extensions.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 472 matching lines @@
         'browser/quota_service.cc',
         'browser/quota_service.h',
         'browser/renderer_startup_helper.cc',
         'browser/renderer_startup_helper.h',
         'browser/runtime_data.cc',
         'browser/runtime_data.h',
         'browser/state_store.cc',
         'browser/state_store.h',
         'browser/uninstall_reason.h',
         'browser/update_observer.h',
+        'browser/updater/default_manifest_fetch_data_delegate.cc',
+        'browser/updater/default_manifest_fetch_data_delegate.h',
+        'browser/updater/manifest_fetch_data.cc',
+        'browser/updater/manifest_fetch_data.h',
+        'browser/updater/manifest_fetch_data_delegate.h',
         'browser/value_store/leveldb_value_store.cc',
         'browser/value_store/leveldb_value_store.h',
         'browser/value_store/testing_value_store.cc',
         'browser/value_store/testing_value_store.h',
         'browser/value_store/value_store.cc',
         'browser/value_store/value_store.h',
         'browser/value_store/value_store_change.cc',
         'browser/value_store/value_store_change.h',
         'browser/value_store/value_store_frontend.cc',
         'browser/value_store/value_store_frontend.h',
@@ skipping 403 matching lines @@
           'browser/api/cast_channel/logging.proto'
       ],
       'variables': {
           'proto_in_dir': 'browser/api/cast_channel',
           'proto_out_dir': 'extensions/browser/api/cast_channel',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ]
 }