Create a project for maintaining default extensions....

chrome/chrome.gyp

 # Copyright (c) 2009 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,
     # Define the common dependencies that contain all the actual
     # Chromium functionality.  This list gets pulled in below by
     # the link of the actual chrome (or chromium) executable on
@@ skipping 230 matching lines @@
           '<(grit_out_dir)',
         ],
       },
       'conditions': [
         ['OS=="win"', {
           'dependencies': ['../build/win/system.gyp:cygwin'],
         }],
       ],
     },
     {
+      'target_name': 'default_extensions',
+      'type': 'none',
+      'msvs_guid': 'DA9BAB64-91DC-419B-AFDE-6FF8C569E83A',
+      'conditions': [
+        ['OS=="win"', {
+          'copies': [
+            {
+              'destination': '<(PRODUCT_DIR)/extensions',
+              'files': [
+                'browser/extensions/default_extensions/external_extensions.json'
+              ]
+            }
+          ],
+        }],
+      ],
+    },
+    {
       'target_name': 'common',
       'type': '<(library)',
       'msvs_guid': '899F1280-3441-4D1F-BA04-CCD6208D9146',
       'dependencies': [
         'chrome_resources',
         'chrome_strings',
         'theme_resources',
         '../app/app.gyp:app_base',
         '../base/base.gyp:base',
         '../base/base.gyp:base_gfx',
@@ skipping 4592 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],
   ],  # 'conditions'
 }