Allow several build directories to be specified to search for symbols

mojo/devtools/common/mojo_debug

 #!/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 codecs
 import logging
 import os.path
 import requests
@@ skipping 269 matching lines @@
   device_parser.add_argument('--adb-path', type=str,
       help='path to the adb tool from the Android SDK (optional)')
   device_subparser = device_parser.add_subparsers(
       help='the command to run')
 
   device_stack_parser = device_subparser.add_parser('stack',
       help='symbolize the crash stacktraces from the device log')
   device_stack_parser.add_argument('--ndk-dir', type=str,
       help='path to the directory containing the Android NDK')
   device_stack_parser.add_argument('--build-dir', type=str,
-      help='path to the build directory')
+      help='list paths to the build directories, separated by commas')
   device_stack_parser.set_defaults(func=_device_stack)
 
 
 def _add_gdb_command(subparsers):
   gdb_parser = subparsers.add_parser(
       'gdb', help='Debug Mojo Shell and its apps using GDB')
   gdb_subparser = gdb_parser.add_subparsers(
       help='Commands to GDB')
 
   gdb_attach_parser = gdb_subparser.add_parser(
@@ skipping 20 matching lines @@
   _add_device_command(subparsers)
   _add_tracing_command(subparsers)
   _add_wm_command(subparsers)
   _add_gdb_command(subparsers)
 
   args = parser.parse_args()
   return args.func(args)
 
 if __name__ == '__main__':
   sys.exit(main())