[tools/perf] Reference legacy_page_test module instead of page_test

tools/perf/benchmarks/media.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 core import perf_benchmark
 
 from telemetry import benchmark
-from telemetry.page import page_test
+from telemetry.page import legacy_page_test
 from telemetry.value import list_of_scalar_values
 from telemetry.value import scalar
 
 from measurements import media
 import page_sets
 
 
-class _MSEMeasurement(page_test.PageTest):
+class _MSEMeasurement(legacy_page_test.LegacyPageTest):
 
   def __init__(self):
     super(_MSEMeasurement, self).__init__()
 
   def ValidateAndMeasurePage(self, page, tab, results):
     media_metric = tab.EvaluateJavaScript('window.__testMetrics')
     trace = media_metric['id'] if 'id' in media_metric else None
     metrics = media_metric['metrics'] if 'metrics' in media_metric else []
     for m in metrics:
       trace_name = '%s.%s' % (m, trace)
@@ skipping 107 matching lines @@
 
   @classmethod
   def Name(cls):
     return 'media.mse_cases'
 
   def SetExtraBrowserOptions(self, options):
     # Needed to allow XHR requests to return stream objects.
     options.AppendExtraBrowserArgs(
         ['--enable-experimental-web-platform-features',
          '--disable-gesture-requirement-for-media-playback'])