Revert of Remove usages of Timeline commands in telemetry

tools/chrome_proxy/integration_tests/network_metrics.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.
 
 import base64
 import gzip
 import hashlib
 import io
 import logging
 import zlib
 
 from metrics import Metric
 from telemetry.page import page_test
 # All network metrics are Chrome only for now.
 from telemetry.core.backends.chrome_inspector import inspector_network
+from telemetry.timeline import recording_options
 from telemetry.value import scalar
 
 
 class NetworkMetricException(page_test.MeasurementFailure):
   pass
 
 
 class HTTPResponse(object):
   """ Represents an HTTP response from a timeline event."""
   def __init__(self, event):
@@ skipping 104 matching lines @@
   def __init__(self):
     super(NetworkMetric, self).__init__()
 
     # Whether to add detailed result for each sub-resource in a page.
     self.add_result_for_resource = False
     self.compute_data_saving = False
     self._events = None
 
   def Start(self, page, tab):
     self._events = None
-    tab.StartTimelineRecording()
+    opts = recording_options.TimelineRecordingOptions()
+    opts.record_network = True
+    tab.StartTimelineRecording(opts)
 
   def Stop(self, page, tab):
     assert self._events is None
     tab.StopTimelineRecording()
 
   def IterResponses(self, tab):
     if self._events is None:
       self._events = tab.timeline_model.GetAllEventsOfName('HTTPResponse')
     if len(self._events) == 0:
       return
@@ skipping 46 matching lines @@
     if self.compute_data_saving:
       if (original_content_length > 0 and
           original_content_length >= content_length):
         saving = (float(original_content_length-content_length) * 100 /
                   original_content_length)
         results.AddValue(scalar.ScalarValue(
             results.current_page, 'data_saving', 'percent', saving))
       else:
         results.AddValue(scalar.ScalarValue(
             results.current_page, 'data_saving', 'percent', 0.0))