Telemetry: featurize tab_switching test for compressed swap performance

tools/telemetry/telemetry/core/util.py

 # Copyright 2012 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 glob
 import imp
 import inspect
 import logging
 import os
 import socket
 import sys
@@ skipping 32 matching lines @@
 
 _counter = [0]
 def _GetUniqueModuleName():
   _counter[0] += 1
   return "page_set_module_" + str(_counter[0])
 
 def GetPythonPageSetModule(file_path):
   return imp.load_source(_GetUniqueModuleName(), file_path)
 
 
-def WaitFor(condition, timeout):
+def WaitFor(condition, timeout, fixed_poll_interval=None):
   """Waits for up to |timeout| secs for the function |condition| to return True.
 
-  Polling frequency is (elapsed_time / 10), with a min of .1s and max of 5s.
+  Polling interval is (elapsed_time / 10), with a min of .1s and max of 5s,
+  unless |fixed_poll_interval| is specified.
 
   Returns:
     Result of |condition| function (if present).
   """
   min_poll_interval =   0.1
   max_poll_interval =   5
   output_interval   = 300
 
   def GetConditionString():
     if condition.__name__ == '<lambda>':
@@ skipping 12 matching lines @@
     now = time.time()
     elapsed_time = now - start_time
     last_output_elapsed_time = now - last_output_time
     if elapsed_time > timeout:
       raise TimeoutException('Timed out while waiting %ds for %s.' %
                              (timeout, GetConditionString()))
     if last_output_elapsed_time > output_interval:
       logging.info('Continuing to wait %ds for %s. Elapsed: %ds.',
                    timeout, GetConditionString(), elapsed_time)
       last_output_time = time.time()
-    poll_interval = min(max(elapsed_time / 10., min_poll_interval),
+    poll_interval = fixed_poll_interval or \
+                    min(max(elapsed_time / 10., min_poll_interval),
                         max_poll_interval)
     time.sleep(poll_interval)
 
 
 def GetUnreservedAvailableLocalPort():
   """Returns an available port on the system.
 
   WARNING: This method does not reserve the port it returns, so it may be used
   by something else before you get to use it. This can lead to flake.
   """
@@ skipping 35 matching lines @@
   """
   name, ext = os.path.splitext(base_name)
   assert ext == '', 'base_name cannot contain file extension.'
   index = 0
   while True:
     output_name = '%s_%03d' % (name, index)
     if not glob.glob(output_name + '.*'):
       break
     index = index + 1
   return output_name