Add a wrapper script which modifies the .isolate on the fly.

chrome/unit_tests.isolate

 # Copyright (c) 2012 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.
 {
   'conditions': [
     ['OS=="android" or OS=="linux"', {
       'variables': {
         'isolate_dependency_untracked': [
           '<(PRODUCT_DIR)/test_data/',
         ],
@@ skipping 51 matching lines @@
         'isolate_dependency_tracked': [
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/unit_tests<(EXECUTABLE_SUFFIX)',
           'browser/safe_browsing/two_phase_testserver.py',
         ],
         'isolate_dependency_untracked': [
           '../net/tools/testserver/',
           '../third_party/pyftpdlib/',
           '../third_party/pywebsocket/',
           '../third_party/tlslite/',
-          '../tools/swarming_client/',
           '<(PRODUCT_DIR)/pyproto/',
         ],
       },
     }],
     ['OS=="linux" or OS=="mac"', {
       'variables': {
         # Can't be enabled on Windows due to http://crbug.com/342913
         'read_only': 1,
       },
     }],
@@ skipping 36 matching lines @@
           '../skia/ext/data/',
           '../ui/base/glib/',
         ],
       },
     }],
   ],
   'includes': [
     '../third_party/icu/icu.isolate',
   ],
 }