swarming: always append task's OS dimension to step name

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.
 
 import collections
 
 from recipe_engine.types import freeze
 
 DEPS = [
   'amp',
@@ skipping 383 matching lines @@
                     '--test-machine-name=\"${buildername}\"',
                     '--build-revision=\"${got_revision}\"',
                   ],
                   'swarming': {'can_use_on_swarming_builders': True},
                 },
             ],
         },
     })) +
     suppress_analyze() +
     api.override_step_data(
-        'telemetry_gpu_unittests (with patch)',
+        'telemetry_gpu_unittests (with patch) on Ubuntu-12.04',
         api.test_utils.canned_isolated_script_output(
             passing=True, is_win=False, swarming=True))
   )
 
   yield (
     api.test('swarming_trigger_failure') +
     props() +
     api.platform.name('linux') +
     api.override_step_data('read test spec', api.json.output({
         'Linux Tests': {
@@ skipping 16 matching lines @@
         'Linux Tests': {
             'gtest_tests': [
                 {
                   'test': 'gl_tests',
                   'swarming': {'can_use_on_swarming_builders': True},
                 },
             ],
         },
     })) +
     suppress_analyze() +
-    api.override_step_data('gl_tests (with patch)',
+    api.override_step_data('gl_tests (with patch) on Ubuntu-12.04',
                            canned_test(passing=False))
   )
 
   yield (
     api.test('amp_test_failure') +
     props(buildername='android_amp',
           mastername='tryserver.chromium.android') +
     api.platform.name('linux') +
     suppress_analyze() +
     api.override_step_data('[collect] base_unittests (with patch)',
@@ skipping 424 matching lines @@
     props(mastername='tryserver.v8',
           buildername='v8_linux_blink_rel',
           patch_project='v8') +
     api.platform.name('linux') +
     suppress_analyze(more_exclusions=['v8/f.*']) +
     api.override_step_data('webkit_tests (with patch)',
         api.test_utils.canned_test_output(passing=False)) +
     api.override_step_data('webkit_tests (without patch)',
         api.test_utils.canned_test_output(passing=True, minimal=True))
   )