Add slow test decorator

tools/chrome_proxy/webdriver/decorators.py

 # Copyright 2017 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 common import ParseFlags
 from common import TestDriver
 
 
@@ skipping 99 matching lines @@
     def wrapper(*args, **kwargs):
       global chrome_version
       if chrome_version == None:
         chrome_version = GetChromeVersion()
       if chrome_version >= milestone:
         func(*args, **kwargs)
       else:
         args[0].skipTest('This test does not run below M%d.' % milestone)
     return wrapper
   return puesdo_wrapper
+
+def Slow(func):
+  def wrapper(*args, **kwargs):
+    if ParseFlags().skip_slow:
+      args[0].skipTest('Skipping slow test.')
+    else:
+      func(*args, **kwargs)
+  return wrapper