Remove --enable-service-worker flag

tools/perf/benchmarks/service_worker.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.
 
 import page_sets
 from telemetry import test
 from telemetry.page import page_measurement
 
 
 class _ServiceWorkerMeasurement(page_measurement.PageMeasurement):
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
-        '--enable-experimental-web-platform-features',
-        '--enable-service-worker'
+        '--enable-experimental-web-platform-features'
       ])
 
   def MeasurePage(self, _, tab, results):
     tab.WaitForJavaScriptExpression('window.done', 40)
     json = tab.EvaluateJavaScript('window.results')
     for key, value in json.iteritems():
       results.Add(key, value['units'], value['value'])
 
 
 class ServiceWorkerPerfTest(test.Test):
   test = _ServiceWorkerMeasurement
   page_set = page_sets.ServiceWorkerPageSet