[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/metrics/speedindex.py

 # Copyright 2013 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 collections
 import logging
 
-from metrics import Metric
 from telemetry.image_processing import image_util
 from telemetry.image_processing import rgba_color
 from telemetry.value import scalar
 
+from metrics import Metric
+
 
 class SpeedIndexMetric(Metric):
   """The speed index metric is one way of measuring page load speed.
 
   It is meant to approximate user perception of page load speed, and it
   is based on the amount of time that it takes to paint to the visual
   portion of the screen. It includes paint events that occur after the
   onload event, and it doesn't include time loading things off-screen.
 
   This speed index metric is based on WebPageTest.org (WPT).
@@ skipping 158 matching lines @@
         else:
           return 0.0
       return 1 - histogram.Distance(final_histogram) / total_distance
 
     self._time_completeness_list = [(time, FrameProgress(hist))
                                     for time, hist in histograms]
 
   def GetTimeCompletenessList(self, tab):
     assert self._time_completeness_list, 'Must call Stop() first.'
     return self._time_completeness_list