Adding comment to inform the user to set up the sandbox manually on Linux.

tools/run-bisect-manual-test.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """Run Manual Test Bisect Tool
 
 An example usage:
 tools/run-bisect-manual-test.py -g 201281 -b 201290
 
+On Linux platform, follow the instructions in this document
+https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment
+to setup the sandbox manually before running the script. Otherwise the script
+fails to launch Chrome and exits with an error.
+
 """
 
 import os
 import subprocess
 import sys
 
 CROS_BOARD_ENV = 'BISECT_CROS_BOARD'
 CROS_IP_ENV = 'BISECT_CROS_IP'
 _DIR_TOOLS_ROOT = os.path.abspath(os.path.dirname(__file__))
 
@@ skipping 81 matching lines @@
   if not options.good_revision:
     error_msg += 'Error: missing required parameter: --good_revision\n'
   if not options.bad_revision:
     error_msg += 'Error: missing required parameter: --bad_revision\n'
 
   if error_msg:
     print error_msg
     parser.print_help()
     return 1
 
+  if sys.platform.startswith('linux'):
+    if not os.environ.get('CHROME_DEVEL_SANDBOX'):
+      print 'SUID sandbox has not been setup.'\
+            ' See https://code.google.com/p/chromium/wiki/'\
+            'LinuxSUIDSandboxDevelopment for more information.'
+      return 1
+
   return _RunBisectionScript(options)
 
 
 if __name__ == '__main__':
   sys.exit(main())