Implement ubertracing.

tools/telemetry/telemetry/timeline/empty_timeline_data_importer.py

-# Copyright 2014 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.
-
-from telemetry.timeline.timeline_data import TimelineData
-
-
-class EmptyTimelineDataImporter(object):
-  """Imports empty TimlineData objects."""
-  def __init__(self, model, timeline_data, import_priority=0):
-    pass
-
-  @staticmethod
-  def CanImport(timeline_data):
-    if not isinstance(timeline_data, TimelineData):
-      return False
-    event_data = timeline_data.EventData()
-    if isinstance(event_data, list):
-      return len(event_data) == 0
-    elif isinstance(event_data, basestring):
-      return len(event_data) == 0
-    return False
-
-  def ImportEvents(self):
-    pass
-
-  def FinalizeImport(self):
-    pass