Explicitly require rooted device in `mojo_test`.

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 44 matching lines @@
       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)
   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"]
 
@@ skipping 26 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())