[Telemetry] Move from telemetry WaitFor to py_utils WaitFor

common/py_utils/py_utils/__init__.py

 #!/usr/bin/env python
 
 # Copyright (c) 2016 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 functools
 import inspect
 import os
 import sys
@@ skipping 91 matching lines @@
     Result of |condition| function (if present).
   """
   def GetConditionString():
     if condition.__name__ == '<lambda>':
       try:
         return inspect.getsource(condition).strip()
       except IOError:
         pass
     return condition.__name__
 
+  # Do an initial check to see if its true.
+  res = condition()
+  if res:
+    return res
   start_time = time.time()
   last_output_time = start_time
   elapsed_time = time.time() - start_time
   while elapsed_time < timeout:
     res = condition()
     if res:
       return res
     now = time.time()
     elapsed_time = now - start_time
     last_output_elapsed_time = now - last_output_time
     if last_output_elapsed_time > OUTPUT_INTERVAL_IN_SECONDS:
       last_output_time = time.time()
     poll_interval = min(max(elapsed_time / 10., MIN_POLL_INTERVAL_IN_SECONDS),
                         MAX_POLL_INTERVAL_IN_SECONDS)
     time.sleep(poll_interval)
   raise TimeoutException('Timed out while waiting %ds for %s.' %
                          (timeout, GetConditionString()))
 
 class TimeoutException(Exception):
   """The operation failed to complete because of a timeout.
 
   It is possible that waiting for a longer period of time would result in a
   successful operation.
   """
   pass