Revert of Remove usages of Timeline commands in telemetry

tools/chrome_proxy/integration_tests/network_metrics.py

Index: tools/chrome_proxy/integration_tests/network_metrics.py
diff --git a/tools/chrome_proxy/integration_tests/network_metrics.py b/tools/chrome_proxy/integration_tests/network_metrics.py
index 9c41dcce37d83164f4e227a54418ff52e1ed40a6..747d60dfb2a7a12f860db5b433682e0cbcbfd94e 100644
--- a/tools/chrome_proxy/integration_tests/network_metrics.py
+++ b/tools/chrome_proxy/integration_tests/network_metrics.py
@@ -13,6 +13,7 @@
 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
 
 
@@ -137,7 +138,9 @@
 
   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