variations uses osname chromeos, not cros.

Bug=chromium:871600

Cq-Include-Trybots: master.tryserver.chromium.perf:obbs_fyi
Change-Id: I09f909050620f8d2e2e9a1fdedbe2c7091732128
Reviewed-on: https://chromium-review.googlesource.com/1173138Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582865}

tools/perf/core/perf_benchmark.py

@@ -113,6 +113,8 @@ class PerfBenchmark(benchmark.Benchmark):
       return 'windows'
     if target_os.startswith('linux'):
       return 'linux'
+    if target_os == 'cros':
+      return 'chromeos'
     return target_os
 
   def _GetVariationsBrowserArgs(self, finder_options):

tools/perf/core/perf_benchmark_unittest.py

@@ -8,7 +8,6 @@ import shutil
 import tempfile
 import unittest
 
-from telemetry import decorators
 from telemetry.internal.browser import browser_finder
 from telemetry.testing import options_for_unittests
 
@@ -35,7 +34,6 @@ class PerfBenchmarkTest(unittest.TestCase):
     self.assertEqual(num_expected_matches, len(ruleset_data_to_copy))
 
 
-  @decorators.Disabled('chromeos')  # crbug.com/871600.
   def testVariationArgs(self):
     benchmark = perf_benchmark.PerfBenchmark()
     options = options_for_unittests.GetCopy()