override chrome:// URLs via 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
@@ skipping 29 matching lines @@
       'browser/download/save_page_browsertest.cc',
       'browser/gtk/bookmark_manager_browsertest.cc',
       'browser/gtk/view_id_util_browsertest.cc',
       'browser/ssl/ssl_browser_tests.cc',
       'browser/extensions/extension_apitest.cc',
       'browser/extensions/extension_apitest.h',
       'browser/extensions/extension_bookmarks_apitest.cc',
       'browser/extensions/extension_browsertest.cc',
       'browser/extensions/extension_browsertest.h',
       'browser/extensions/extension_browsertests_misc.cc',
+      'browser/extensions/extension_override_apitest.cc',
       'browser/extensions/extension_startup_unittest.cc',
     ],
     'browser_tests_sources_win_specific': [
       'browser/extensions/extension_devtools_browsertest.cc',
       'browser/extensions/extension_devtools_browsertest.h',
       'browser/extensions/extension_devtools_browsertests.cc',
       'browser/extensions/extension_shelf_model_unittest.cc',
       'browser/views/browser_views_accessibility_browsertest.cc',
       'browser/views/find_bar_win_browsertest.cc',
       # TODO(jam): http://crbug.com/15101 These tests fail on Linux and Mac.
@@ skipping 5785 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'
 }