Clear the network service disk cache for each apptest run.

mojo/devtools/common/mojo_test

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """Test runner for Mojo application tests.
 
 TODO(vtl|msw): Add a way of specifying data dependencies.
 """
 
@@ skipping 32 matching lines @@
 
 |test_list_file| may reference the |target_os| global that will be any of
 ['android', 'linux'], indicating the system on which the tests are to be run.
 
 Any arguments not recognized by the script will be passed on as shell arguments.
 """
 
 _logger = logging.getLogger()
 
 _CACHE_SERVICE_URL = 'mojo:url_response_disk_cache'
+_NETWORK_SERVICE_URL = 'mojo:network_service'
 
 
 def main():
   parser = argparse.ArgumentParser(
       formatter_class=argparse.RawDescriptionHelpFormatter,
       description=_DESCRIPTION)
   parser.add_argument("test_list_file", type=file,
                       help="a file listing apptests to run")
   shell_config.add_shell_arguments(parser)
 
   script_args, shell_args = parser.parse_known_args()
 
   try:
     config = shell_config.get_shell_config(script_args)
     if script_args.android:
       # We need root to have the stdout of the shell available on the host.
       config.require_root = True
     shell, common_shell_args = shell_arguments.get_shell(config, shell_args)
-    # Tests must be reproducible. Start with an empty cache.
+    # Tests must be reproducible, start with empty caches.
     common_shell_args.append(
         "--args-for=%s %s" % (_CACHE_SERVICE_URL, "--clear"))
+    common_shell_args.append(
+        "--args-for=%s %s" % (_NETWORK_SERVICE_URL, "--clear"))
   except shell_config.ShellConfigurationException as e:
     print e
     return 1
 
   target_os = "android" if script_args.android else "linux"
   test_list_globals = {"target_os": target_os}
   exec script_args.test_list_file in test_list_globals
   test_list = test_list_globals["tests"]
 
   succeeded = True
@@ skipping 25 matching lines @@
       print "Unrecognized test type in %r" % test_dict
 
     print "Succeeded" if apptest_result else "Failed"
     _logger.info("Completed: %s" % test_name)
     if not apptest_result:
       succeeded = False
   return 0 if succeeded else 1
 
 if __name__ == '__main__':
   sys.exit(main())