Remove use of "use_mirror" recipe property.

scripts/slave/recipe_modules/perf_dashboard/example.py

 # Copyright 2014 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.
 
 DEPS = [
     'perf_dashboard',
     'recipe_engine/path',
     'recipe_engine/json',
     'recipe_engine/platform',
     'recipe_engine/properties',
@@ skipping 40 matching lines @@
       'post_data': {
           'try_job_id': 1,
           'status': 'completed'
       },
       'text': '',
       'status_code': 200
   }
   for platform in ('linux', 'win', 'mac'):
     for production in (True, False):
       yield (api.test('%s%s' %
-                      (platform, '_use_mirror'
-                       if production else '')) + api.platform.name(platform) +
-             api.properties(use_mirror=production,
+                      (platform, '_testing'
+                       if not production else '')) +
+             api.platform.name(platform) +
+             api.properties(perf_production=production,
                             slavename='multivm-windows-release',
                             buildername='multivm-windows-perf-be',
                             buildnumber=75,
                             mastername='client.dart.fyi') +
              api.step_data('Post bisect results',
                            stdout=api.json.output(bisect_response)))