Add infra_libs as a bootstrap dependency.

infra_libs/time_functions/timestamp.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.
-
-
-"""Provides common timestamp functions."""
-
-import datetime
-import pytz
-
-
-def utctimestamp(dt):
-  """Converts a datetime object into a floating point timestamp since the epoch.
-
-  dt is the datetime to convert. If dt is a naive (non-tz-aware) object, it
-     will implicitly be treated as UTC.
-  """
-  epoch = datetime.datetime.utcfromtimestamp(0).replace(tzinfo=pytz.UTC)
-  # This check is from http://stackoverflow.com/a/27596917/3984761.
-  if dt.tzinfo is None or dt.tzinfo.utcoffset(dt) is None:
-    dt = dt.replace(tzinfo=pytz.UTC)
-  return (dt - epoch).total_seconds()
-
-
-def utcnow_ts():  # pragma: no cover
-  """Returns the floating point number of seconds since the UTC epoch."""
-  return utctimestamp(datetime.datetime.utcnow())