Stop using third_party\python_26 for many tests.

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 79 matching lines @@
           '<(PRODUCT_DIR)/clearkeycdmadapter.dll',
           '<(PRODUCT_DIR)/content_shell.pak',
           '<(PRODUCT_DIR)/plugins/npTestNetscapePlugIn.dll',
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.dll',
         ],
         'isolate_dependency_untracked': [
           # The two directories below are only needed for
           # WorkerXHRHttpLayoutTest.Tests which are currently disabled.
           #'../third_party/cygwin/',
           #'../third_party/perl/perl/',
-          '../third_party/python_26/',
         ],
       },
     }],
   ],
 }