webrtc: Fix missing port forwarding on CrOS

telemetry/telemetry/core/platform.py

 # Copyright 2012 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 as real_logging
 import os
 import sys
 
 from telemetry.core import local_server
 from telemetry.core import memory_cache_http_server
 from telemetry.core import network_controller
 from telemetry.core import tracing_controller
 from telemetry.core import util
+from telemetry.internal import forwarders
 from telemetry.internal.platform import (platform_backend as
                                          platform_backend_module)
 
 from py_utils import discover
 
 _host_platform = None
 # Remote platform is a dictionary from device ids to remote platform instances.
 _remote_platforms = {}
 
 
@@ skipping 380 matching lines @@
       if paths and self.http_server.paths == paths:
         return False
 
       self.http_server.Close()
 
     if not paths:
       return False
 
     server = memory_cache_http_server.MemoryCacheHTTPServer(paths)
     self.StartLocalServer(server)
+
+    # Requires port forwarding if browser is on remote machine, and
+    # replaces the http_server port number with the one resolved by
+    # remote machine with ssh remote port forwarding.
+    if not self._platform_backend._cri.local:

[nednguyen, 2017/07/18 00:44:58]

This seems very wrong. Not all platform_backend have "._cri" object, so this
will break on non ChromeOS backend.

[cywang, 2017/07/18 09:03:32]

Thanks a lot, I change the section to make it CrOS only.

+      forwarder = self._platform_backend.forwarder_factory.Create(
+          forwarders.PortPair(self.http_server.port, 0),
+          use_remote_port_forwarding=True)
+      self.http_server.port = forwarder.host_port
     return True
 
   def StopAllLocalServers(self):
     self._local_server_controller.Close()
 
   @property
   def local_servers(self):
     """Returns the currently running local servers."""
     return self._local_server_controller.local_servers
 
   def HasBattOrConnected(self):
     return  self._platform_backend.HasBattOrConnected()
 
   def WaitForBatteryTemperature(self, temp):
     """Waits for the battery on the device under test to cool down to temp.
 
     Args:
       temp: temperature target in degrees C.
     """
     return self._platform_backend.WaitForBatteryTemperature(temp)