[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/measurements/task_execution_time_unittest.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 measurements import task_execution_time
+from telemetry.core import wpr_modes
 from telemetry import decorators
-from telemetry.core import wpr_modes
 from telemetry.page import page as page_module
 from telemetry.results import page_test_results
 from telemetry.timeline import model as model_module
 from telemetry.timeline import slice as slice_data
 from telemetry.unittest_util import options_for_unittests
 from telemetry.unittest_util import page_test_test_case
 
+from measurements import task_execution_time
+
 
 class TestTaskExecutionTimePage(page_module.Page):
 
   def __init__(self, page_set, base_dir):
     super(TestTaskExecutionTimePage, self).__init__(
         'file://blank.html', page_set, base_dir)
 
   def RunPageInteractions(self, action_runner):
     interaction = action_runner.BeginGestureInteraction(
         'ScrollAction')
@@ skipping 239 matching lines @@
         None,
         'category',
         name,
         timestamp,
         duration,
         timestamp,
         duration,
         [])
     self._renderer_thread.all_slices.append(new_slice)
     return new_slice