Don't fail taskkill on chrome processes alive

tools/task_kill.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 #
 
 # A script to kill hanging processs. The tool will return non-zero if any
 # process was actually found.
 #
@@ skipping 154 matching lines @@
       KillWindows(pid)
     else:
       KillPosix(pid)
     print("Killed pid: %s" % pid)
   if len(pids) == 0:
     print("  No %s processes found." % name)
   return len(pids)
 
 def KillBrowsers():
   status = Kill('firefox')
-  status += Kill('chrome')
+  # We don't give error on killing chrome. It happens quite often that the
+  # browser controller fails in killing chrome, so we silently do it here.
+  Kill('chrome')
   status += Kill('iexplore')
   status += Kill('safari')
   status += Kill('content_shell')
   return status
 
 def KillVCSystems():
   status = Kill('git')
   status += Kill('svn')
   return status
 
 def KillDart():
   status = Kill("dart")
   return status
 
 def Main():
   options = GetOptions()
   status = 0
   if options.kill_dart:
     status += KillDart()
   if options.kill_vc:
     status += KillVCSystems()
   if options.kill_browsers:
     status += KillBrowsers()
   return status
 
 if __name__ == '__main__':
   sys.exit(Main())