[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/metrics/loading.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.
 
+from telemetry.value import scalar
+
 from metrics import Metric
-from telemetry.value import scalar
+
 
 class LoadingMetric(Metric):
   """A metric for page loading time based entirely on window.performance"""
 
   def Start(self, page, tab):
     raise NotImplementedError()
 
   def Stop(self, page, tab):
     raise NotImplementedError()
 
@@ skipping 43 matching lines @@
         float(load_timings['responseStart']) - load_timings['requestStart'])
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'request_duration', 'ms', request_duration,
         important=False))
 
     response_duration = (
         float(load_timings['responseEnd']) - load_timings['responseStart'])
     results.AddValue(scalar.ScalarValue(
         results.current_page, 'response_duration', 'ms', response_duration,
         important=False))