Update service_worker to use results.AddValue(...)

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 benchmark
 from telemetry.page import page_measurement
+from telemetry.value import scalar
 
 
 class _ServiceWorkerMeasurement(page_measurement.PageMeasurement):
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
         '--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'])
+      results.AddValue(scalar.ScalarValue(
+          results.current_page, key, value['units'], value['value']))
 
 
 @benchmark.Disabled
 class ServiceWorkerPerfTest(benchmark.Benchmark):
   test = _ServiceWorkerMeasurement
   page_set = page_sets.ServiceWorkerPageSet