Mark all chromium test swarming task requests as idempotent.

scripts/slave/recipes/chromium_trybot.py

 # Copyright 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.
 
 DEPS = [
   'bot_update',
   'chromium',
   'chromium_tests',
   'gclient',
   'isolate',
@@ skipping 875 matching lines @@
 
     return tests, bot_update_step
 
   mastername = api.properties.get('mastername')
   buildername = api.properties.get('buildername')
   bot_config = get_bot_config(mastername, buildername)
   api.swarming.set_default_dimension('pool', 'Chrome')
   api.swarming.default_priority = build_to_priority(api.properties)
   api.swarming.add_default_tag('project:chromium')
   api.swarming.add_default_tag('purpose:pre-commit')
-  # TODO(maruel): Soon!
-  # api.swarming.default_idempotent = True
+  api.swarming.default_idempotent = True
 
   # Differentiate between try jobs and CQ jobs. Always find out who made the CL.
   requestor = api.properties.get('requestor')
   if requestor == 'commit-bot@chromium.org':
     api.swarming.add_default_tag('purpose:CQ')
     blamelist = api.properties.get('blamelist')
     if len(blamelist) == 1:
       requestor = blamelist[0]
   else:
     api.swarming.add_default_tag('purpose:ManualTS')
@@ skipping 638 matching lines @@
           },
         ],
       })
     ) +
     api.override_step_data(
       'analyze',
       api.json.output({'status': 'Found dependency',
                        'targets': ['browser_tests', 'base_unittests'],
                        'build_targets': ['base_unittests']}))
   )