[telemetry] Add a webdriver backend with support for IE.

tools/telemetry/telemetry/core/chrome/cros_browser_backend.py

 # Copyright (c) 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
 import os
 import subprocess
 
 from telemetry.core import exceptions
 from telemetry.core import util
 from telemetry.core.chrome import browser_backend
@@ skipping 210 matching lines @@
     return bool(self.pid)
 
   def GetStandardOutput(self):
     return 'Cannot get standard output on CrOS'
 
   def GetStackTrace(self):
     return 'Cannot get stack trace on CrOS'
 
   def CreateForwarder(self, *port_pairs):
     assert self._cri
-    return (browser_backend.DoNothingForwarder(*port_pairs) if self._cri.local
+    return (util.DoNothingForwarder(*port_pairs) if self._cri.local
         else SSHForwarder(self._cri, 'R', *port_pairs))
 
   def _RestartUI(self):
     if self._cri:
       logging.info('(Re)starting the ui (logs the user out)')
       if self._cri.IsServiceRunning('ui'):
         self._cri.RunCmdOnDevice(['restart', 'ui'])
       else:
         self._cri.RunCmdOnDevice(['start', 'ui'])
 
@@ skipping 132 matching lines @@
   @property
   def url(self):
     assert self._proc
     return 'http://localhost:%i' % self._host_port
 
   def Close(self):
     if self._proc:
       self._proc.kill()
       self._proc = None