[tools/perf] Reference legacy_page_test module instead of page_test

tools/perf/measurements/thread_times.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.page import page_test
+from telemetry.page import legacy_page_test
 from telemetry.timeline import tracing_category_filter
 from telemetry.web_perf.metrics import layout
 
 from measurements import timeline_controller
 from metrics import timeline
 
 
-class ThreadTimes(page_test.PageTest):
+class ThreadTimes(legacy_page_test.LegacyPageTest):
 
   def __init__(self, report_silk_details=False):
     super(ThreadTimes, self).__init__()
     self._timeline_controller = None
     self._report_silk_details = report_silk_details
 
   def WillNavigateToPage(self, page, tab):
     self._timeline_controller = timeline_controller.TimelineController(
         enable_auto_issuing_record=False)
     if self._report_silk_details:
@@ skipping 16 matching lines @@
       metric.details_to_report = timeline.ReportSilkDetails
     metric.AddResults(self._timeline_controller.model, renderer_thread,
                       self._timeline_controller.smooth_records, results)
     layout_metric = layout.LayoutMetric()
     layout_metric.AddResults(self._timeline_controller.model, renderer_thread,
                              self._timeline_controller.smooth_records, results)
 
   def DidRunPage(self, platform):
     if self._timeline_controller:
       self._timeline_controller.CleanUp(platform)