Handle repack.py and .pak files in the GYP-based build.

tools/data_pack/repack.py

 #!/usr/bin/python
 # Copyright (c) 2008 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.
 
 """A simple utility function to merge data pack files into a single data pack.
 See base/pack_file* for details about the file format.
 """
 
 import exceptions
@@ skipping 12 matching lines @@
     # Make sure we have no dups.
     duplicate_keys = set(new_resources.keys()) & set(resources.keys())
     if len(duplicate_keys) != 0:
       raise exceptions.KeyError("Duplicate keys: " + str(list(duplicate_keys)))
 
     resources.update(new_resources)
 
   data_pack.WriteDataPack(resources, output_file)
 
 def main(argv):
-  if len(argv) < 4:
-    print ("Usage:\n  %s <output_filename> <input_file1> <input_file2> "
-        "[input_file3] ..." % argv[0])
+  if len(argv) < 3:
+    print ("Usage:\n  %s <output_filename> <input_file1> [input_file2] ... " %
+           argv[0])
     sys.exit(-1)
   RePack(argv[1], argv[2:])
 
 if '__main__' == __name__:
   main(sys.argv)