Display proper error if root path argument is not an existing directory

chrome-update.py

 #!/usr/bin/python
 # Copyright (c) 2009 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.
 
 # Author: mpcomplete
 #
 # This script updates and does a clean build of chrome for you.
 # Usage: python chrome-update.py C:\path\to\chrome\trunk
 #
@@ skipping 126 matching lines @@
 
   if options.print_latest:
     print GetRevision() or "HEAD"
     sys.exit(0)
 
   if not args:
     Message("Usage: %s <path\\to\\chrome\\root> [options]" % sys.argv[0])
     sys.exit(1)
 
   chrome_root = args[0]
+  if not os.path.isdir(chrome_root):
+    Message("Path to chrome root (%s) not found." % repr(chrome_root))
+    sys.exit(1)
 
   if not options.nosync:
     rv = DoUpdate(chrome_root)
     if rv != 0:
       Message("Update Failed.  Bailing.")
       sys.exit(rv)
 
   chrome_sln = FixupPath(options.solution)
   rv = DoBuild(chrome_root, chrome_sln, options.clean, "Debug")
   if rv != 0:
     Message("Debug build failed.  Sad face :(")
 
   if options.release:
     rv = DoBuild(chrome_root, chrome_sln, options.clean, "Release")
     if rv != 0:
       Message("Release build failed.  Sad face :(")
 
   if rv != 0:
     sys.exit(rv)
 
   Message("Success!")
 
 if __name__ == "__main__":
   Main()