[Telemetry] Add API for updating ts_proxy_server's traffic settings

telemetry/telemetry/internal/platform/network_controller_backend.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 logging
 import os
 import shutil
 import tempfile
 
 from telemetry.internal.util import wpr_server
@@ skipping 256 matching lines @@
     host_ip = None
     if not use_live_traffic:
       host_ip = self.host_ip
     self._ts_proxy_server = ts_proxy_server.TsProxyServer(host_ip=host_ip)
     self._ts_proxy_server.StartServer()
     return self._ts_proxy_server.port
 
   @property
   def forwarder(self):
     return self._forwarder
+
+  @property
+  def ts_proxy_server(self):
+    return self._ts_proxy_server