Turn off ash and aura by default on linux blink bots.

masters/master.chromium.webkit/master_linux_webkit_pinned_cfg.py

 # 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.
 
 from master import master_config
 from master.factory import chromium_factory
 
 import master_site_config
 
 ActiveMaster = master_site_config.ChromiumWebkit
@@ skipping 33 matching lines @@
         '--build-tool=ninja',
         '--compiler=goma',
         '--',
         'all_webkit',
     ],
     factory_properties={
         'additional_expectations': [
             ['webkit', 'tools', 'layout_tests', 'test_expectations.txt' ],
         ],
         'archive_webkit_results': ActiveMaster.is_production_host,
-        'gclient_env': { 'GYP_GENERATORS': 'ninja' },
+        'gclient_env': {
+            'GYP_DEFINES': 'use_ash=0 use_aura=0',
+            'GYP_GENERATORS':'ninja',
+        },
         'generate_gtest_json': True,
         'test_results_server': 'test-results.appspot.com',
     }))
 
 def Update(_config, _active_master, c):
   return helper.Update(c)