Add ability to customise Virtual Me2Me X session.

remoting/tools/me2me_virtual_host.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 # Virtual Me2Me implementation.  This script runs and manages the processes
 # required for a Virtual Me2Me desktop, which are: X server, X desktop
 # session, and Host process.
 # This script is intended to run continuously as a background daemon
 # process, running under an ordinary (non-root) user account.
@@ skipping 472 matching lines @@
 
   Returns:
     A string containing the command to run, or a list of strings containing
     the executable program and its arguments, which is suitable for passing as
     the first parameter of subprocess.Popen().  If a suitable session cannot
     be found, returns None.
   """
   if XSESSION_COMMAND is not None:
     return XSESSION_COMMAND
 
+  # Use a custom startup file if present
+  startup_file = os.path.expanduser("~/.chrome-remote-desktop-session")
+  if os.path.exists(startup_file):
+    # Use the same logic that a Debian system typically uses with ~/.xsession
+    # (see /etc/X11/Xsession.d/50x11-common_determine-startup), to determine
+    # exactly how to run this file.
+    if os.access(startup_file, os.X_OK):
+      return startup_file
+    else:
+      shell = os.environ.get("SHELL", "sh")
+      return [shell, startup_file]
+
   # Unity-2d would normally be the preferred choice on Ubuntu 12.04.  At the
   # time of writing, this session does not work properly (missing launcher and
   # panel), so gnome-session-fallback is used in preference.
   # "unity-2d-panel" was chosen here simply because it appears in the TryExec
   # line of the session's .desktop file; other choices might be just as good.
   for test_file, command in [
     ("/usr/bin/gnome-session-fallback",
       ["/etc/X11/Xsession", "gnome-session-fallback"]),
     ("/etc/gdm/Xsession", "/etc/gdm/Xsession"),
     ("/usr/bin/unity-2d-panel",
@@ skipping 368 matching lines @@
         logging.info("OAuth credentials are invalid - exiting.")
         try:
           os.remove(auth.config_file)
         except:
           pass
         return 0
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG)
   sys.exit(main())