Adding mozilla libraries required by Firefox interop test.

third_party/mozdownload/mozdownload/timezones.py

+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""Module for providing specific timezones"""
+
+from datetime import datetime, timedelta, tzinfo
+
+
+class PacificTimezone(tzinfo):
+    """Class to set the timezone to PST/PDT and automatically adjusts
+    for daylight saving.
+    """
+
+    def utcoffset(self, dt):
+        return timedelta(hours=-8) + self.dst(dt)
+
+
+    def tzname(self, dt):
+        return "Pacific"
+
+
+    def dst(self, dt):
+        # Daylight saving starts on the second Sunday of March at 2AM standard
+        dst_start_date = self.first_sunday(dt.year, 3) + timedelta(days=7) \
+                                                       + timedelta(hours=2)
+        # Daylight saving ends on the first Sunday of November at 2AM standard
+        dst_end_date = self.first_sunday(dt.year, 11) + timedelta(hours=2)
+
+        if dst_start_date <= dt.replace(tzinfo=None) < dst_end_date:
+            return timedelta(hours=1)
+        else:
+            return timedelta(0)
+
+
+    def first_sunday(self, year, month):
+        date = datetime(year, month, 1, 0)
+        days_until_sunday = 6 - date.weekday()
+
+        return date + timedelta(days=days_until_sunday)