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

content/content_browsertests.isolate

 # Copyright (c) 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.
 {
   'conditions': [
     ['OS=="android"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/content_shell/assets/content_shell.pak',
         ],
@@ skipping 33 matching lines @@
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/content_browsertests<(EXECUTABLE_SUFFIX)',
         ],
         'isolate_dependency_untracked': [
           '../net/tools/testserver/',
           '../third_party/WebKit/Tools/Scripts/',
           '../third_party/lighttpd/',
           '../third_party/pyftpdlib/',
           '../third_party/pywebsocket/',
           '../third_party/tlslite/',
-          '../tools/swarming_client/',
         ],
       },
     }],
     ['OS=="mac"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/clearkeycdmadapter.plugin',
           '<(PRODUCT_DIR)/content_resources.pak',
           '<(PRODUCT_DIR)/ffmpegsumo.so',
           '<(PRODUCT_DIR)/plugins/TestNestscapePlugin.plugin',
@@ skipping 21 matching lines @@
           '<(PRODUCT_DIR)/clearkeycdm.dll',
           '<(PRODUCT_DIR)/clearkeycdmadapter.dll',
           '<(PRODUCT_DIR)/content_shell.pak',
           '<(PRODUCT_DIR)/plugins/np_test_netscape_plugin.dll',
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.dll',
         ],
       },
     }],
   ],
 }