[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/metrics/startup_metric.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 json
 import logging
 
-from metrics import Metric
-
 from telemetry.core import exceptions
 from telemetry.value import histogram_util
 from telemetry.value import scalar
 
+from metrics import Metric
+
 
 class StartupMetric(Metric):
   "A metric for browser startup time."
 
   HISTOGRAMS_TO_RECORD = {
     'messageloop_start_time' :
         'Startup.BrowserMessageLoopStartTimeFromMainEntry',
     'window_display_time' : 'Startup.BrowserWindowDisplay',
     'open_tabs_time' : 'Startup.BrowserOpenTabs'}
 
@@ skipping 93 matching lines @@
 
       results.AddValue(scalar.ScalarValue(
           results.current_page, display_name, 'ms', measured_time))
 
     # Get tab load times.
     browser_main_entry_time_ms = self._GetBrowserMainEntryTime(tab)
     if (browser_main_entry_time_ms is None):
       print "Outdated Chrome version, browser main entry time not supported."
       return
     self._RecordTabLoadTimes(tab, browser_main_entry_time_ms, results)