[tools/perf] Enable many more lint checks for perf directory.

tools/perf/page_sets/memory_top_10_mobile.py

 # Copyright 2015 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 re
 
 from telemetry.page import page as page_module
 from telemetry.page import shared_page_state
 from telemetry import story
 
@@ skipping 59 matching lines @@
 
   def __init__(self):
     super(MemoryTop10Mobile, self).__init__(
         archive_data_file='data/memory_top_10_mobile.json',
         cloud_storage_bucket=story.PARTNER_BUCKET)
 
     for url in top_10_mobile.URL_LIST:
       # We name pages so their foreground/background counterparts are easy
       # to identify. For example 'http://google.com' becomes
       # 'http_google_com' and 'after_http_google_com' respectively.
-      name = re.sub('\W+', '_', url)
+      name = re.sub(r'\W+', '_', url)
       self.AddStory(ForegroundPage(self, name, url))
       self.AddStory(BackgroundPage(self, 'after_' + name))
 
 
 class MemoryTop10MobileRealistic(MemoryTop10Mobile):
   """Top 10 mobile user story in realistic mode.
 
   This means, in particular, neither forced GCs nor clearing caches.
   """
   DETERMINISTIC_MODE = False