[ChromeDriver] Add timeout to waiting for ChromeDriver to shut down

Bug: chromedriver:3042
Change-Id: I8ebec3e58904e63926aa276902c7a92559c8ab66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1785681Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Tatiana Buldina <buldina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693810}

chrome/test/chromedriver/server/server.py

@@ -6,9 +6,23 @@ import atexit
 import os
 import socket
 import subprocess
+import threading
 import time
 import urllib2
 
+def terminate_process(proc):
+  """Terminates the process.
+
+  If an error occurs ignore it, just print out a message.
+
+  Args:
+    proc: A subprocess.
+  """
+  try:
+    proc.terminate()
+  except OSError as ex:
+    print 'Error while killing a process: %s' % ex
+
 
 class Server(object):
   """A running ChromeDriver server."""
@@ -100,5 +114,8 @@ class Server(object):
       urllib2.urlopen(self.GetUrl() + '/shutdown', timeout=10).close()
     except:
       self._process.terminate()
+    timer = threading.Timer(5, terminate_process, [self._process])
+    timer.start()
     self._process.wait()
+    timer.cancel()
     self._process = None