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

telemetry/telemetry/internal/util/ts_proxy_server.py

 # Copyright 2016 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.
 
 """Start and stop tsproxy."""
 
 import logging
 import os
 import re
 import subprocess
@@ skipping 95 matching lines @@
 
   def UpdateOutboundPorts(self, http_port, https_port, timeout=5):
     assert http_port and https_port
     assert http_port != https_port
     assert isinstance(http_port, int) and isinstance(https_port, int)
     assert 1 <= http_port <= 65535
     assert 1 <= https_port <= 65535
     self._IssueCommand('set mapports 443:%i,*:%i' % (https_port, http_port),
                        timeout)
 
+  def UpdateTrafficSettings(self, round_trip_latency_ms=0,
+      download_bandwidth_kbps=0, upload_bandwidth_kbps=0, timeout=5):
+    self._IssueCommand('set rtt %s' % round_trip_latency_ms, timeout)
+    self._IssueCommand('set inkbps %s' % download_bandwidth_kbps, timeout)
+    self._IssueCommand('set outkbps %s' % upload_bandwidth_kbps, timeout)
+
   def StopServer(self):
     """Stop TsProxy Server."""
     if not self._is_running:
       logging.warning('Attempting to stop TsProxy server that is not running.')
       return
     if self._proc:
       self._proc.terminate()
       self._proc.wait()
     err = self._proc.stderr.read()
     self._proc = None
     self._port = None
     self._is_running = False
     return err
 
   def __enter__(self):
     """Add support for with-statement."""
     self.StartServer()
     return self
 
   def __exit__(self, unused_exc_type, unused_exc_val, unused_exc_tb):
     """Add support for with-statement."""
     self.StopServer()