Stop using third_party\python_26 for many tests.

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 90 matching lines @@
     }],
     ['OS=="win"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/ffmpegsumo.dll',
           '<(PRODUCT_DIR)/icudt.dll',
         ],
         'isolate_dependency_untracked': [
           '../ppapi/lib/gl/include/KHR/',
           '../skia/ext/data/',
-          '../third_party/python_26/',
           '../ui/base/glib/',
         ],
       },
     }],
   ],
 }