Add a --no_install option to shelldb

sky/tools/shelldb

 #!/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.
 
 from skypy.skyserver import SkyServer
 import argparse
 import json
 import logging
 import os
@@ skipping 95 matching lines @@
     return _convert_to_sky_url(url)
 
 
 class StartSky(object):
     def add_subparser(self, subparsers):
         start_parser = subparsers.add_parser('start',
             help='launch SKyShell.apk on the device')
         start_parser.add_argument('build_dir', type=str)
         start_parser.add_argument('url_or_path', nargs='?', type=str,
             default=DEFAULT_URL)
+        start_parser.add_argument('--no_install', action="store_false",
+            default=True, dest="install",
+            help="Don't install SkyDemo.apk before starting")
         start_parser.set_defaults(func=self.run)
 
     def _server_root_for_url(self, url_or_path):
         path = os.path.abspath(url_or_path)
         if os.path.commonprefix([path, SRC_ROOT]) == SRC_ROOT:
             server_root = SRC_ROOT
         else:
             server_root = os.path.dirname(path)
             logging.warn(
                 '%s is outside of mojo root, using %s as server root' %
@@ skipping 26 matching lines @@
             sdk_root,
         ])
 
         sky_server = self._sky_server_for_args(args, packages_root)
         pids['sky_server_pid'] = sky_server.start()
         pids['sky_server_port'] = sky_server.port
         pids['sky_server_root'] = sky_server.root
 
         pids['build_dir'] = os.path.abspath(args.build_dir)
 
-        subprocess.check_call([ADB_PATH, 'install', '-r', apk_path])
+        if args.install:
+            subprocess.check_call([ADB_PATH, 'install', '-r', apk_path])
 
         port_string = 'tcp:%s' % sky_server.port
         subprocess.check_call([
             ADB_PATH, 'reverse', port_string, port_string
         ])
         pids['remote_sky_server_port'] = sky_server.port
 
         subprocess.check_call([ADB_PATH, 'shell',
             'am', 'start',
             '-a', 'android.intent.action.VIEW',
@@ skipping 117 matching lines @@
         args = parser.parse_args()
         pids = Pids.read_from(PID_FILE_PATH, PID_FILE_KEYS)
         exit_code = args.func(args, pids)
         # We could do this with an at-exit handler instead?
         pids.write_to(PID_FILE_PATH)
         sys.exit(exit_code)
 
 
 if __name__ == '__main__':
     SkyShellRunner().main()