Don't spawn debugger.mojo by default in `mojo_run`.

mojo/devtools/common/mojo_run

 #!/usr/bin/env python
 # Copyright 2014 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 argparse
 import logging
 import sys
 
 from devtoolslib import shell_arguments
@@ skipping 22 matching lines @@
 """
 
 
 # Port on which the mojo:debugger http server will be available on the host
 # machine.
 _MOJO_DEBUGGER_PORT = 7777
 _DEFAULT_WM = 'https://core.mojoapps.io/kiosk_wm.mojo'
 
 _LEGACY_WM_URL = 'mojo:window_manager'
 _WM_URL = 'https://core.mojoapps.io/window_manager.mojo'
+_DEBUGGER_URL = 'https://core.mojoapps.io/debugger.mojo'
 
 
 def _configure_debugger(shell):
-  """Configures mojo:debugger to run and sets up port forwarding for its http
+  """Configures debugger.mojo to run and sets up port forwarding for its http
   server if the shell is running on a device.
 
   Returns:
     Arguments that need to be appended to the shell argument list in order to
     run with the debugger.
   """
   shell.forward_host_port_to_shell(_MOJO_DEBUGGER_PORT)
-  return ['mojo:debugger %d' % _MOJO_DEBUGGER_PORT]
+  return ['%s %d' % (_DEBUGGER_URL, _MOJO_DEBUGGER_PORT)]
 
 
 def main():
   logging.basicConfig()
 
   parser = argparse.ArgumentParser(usage=_USAGE, description=_DESCRIPTION)
   shell_config.add_shell_arguments(parser)
 
   parser.add_argument('--embed', type=str,
                       help='Url to be embedded in the window manager.')
   parser.add_argument('--window-manager', default=_DEFAULT_WM,
                       help='Window manager app to be mapped as '
                       'mojo:window_manager. By default it is ' +
                       _DEFAULT_WM)
-  parser.add_argument('--no-debugger', action="store_true",
-                      help='Do not spawn mojo:debugger.')
+  parser.add_argument('--debugger', action="store_true",
+                      help='Run debugger.mojo along with the app.')
 
   script_args, shell_args = parser.parse_known_args()
 
   try:
     config = shell_config.get_shell_config(script_args)
     shell, shell_args = shell_arguments.get_shell(config, shell_args)
   except shell_config.ShellConfigurationException as e:
     print e
     return 1
 
   shell_args = shell_arguments.append_to_argument(shell_args, '--url-mappings=',
                                                   '%s=%s' % (_LEGACY_WM_URL,
                                                   script_args.window_manager))
   shell_args = shell_arguments.append_to_argument(shell_args, '--url-mappings=',
                                                   '%s=%s' % (_WM_URL,
                                                   script_args.window_manager))
 
   if script_args.embed:
     shell_args.append('%s %s' % (script_args.window_manager, script_args.embed))
 
-  if not script_args.no_debugger:
+  if script_args.debugger:
     if script_args.verbose:
       print 'Spawning mojo:debugger, use `mojo_debug` to inspect the shell.'
       print 'Note that mojo:debugger will prevent the shell from terminating,'
       print '  pass --no-debugger to skip spawning mojo:debugger.'
     shell_args.extend(_configure_debugger(shell))
 
   if script_args.verbose:
     print "Shell arguments: " + str(shell_args)
 
   shell.run(shell_args)
   return 0
 
 
 if __name__ == "__main__":
   sys.exit(main())