[telemetry] Cleanups for benchmarks importing page sets.

tools/perf/page_sets/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.
 
 from telemetry.page import page
 from telemetry.page import page_set
 from telemetry.page.actions import all_page_actions as actions
 
 
 archive_data_file_path = 'data/service_worker.json'
 
 
 class ServiceWorkerPage(page.Page):
   def RunNavigateSteps(self, action_runner):
     action_runner.RunAction(actions.NavigateAction())
     action_runner.RunAction(actions.WaitAction({'javascript': 'window.done'}))
 
 
 class ServiceWorkerPageSet(page_set.PageSet):
+  """ServiceWorker performance tests"""
+
   def __init__(self):
     super(ServiceWorkerPageSet, self).__init__(
-        description='ServiceWorker performance tests',
         archive_data_file=archive_data_file_path,
         make_javascript_deterministic=False)
 
     self.AddPage(ServiceWorkerPage('http://localhost:8091/index.html', self))