Fix python scripts in src/ppapi/

ppapi/generators/generator.py

-#!/usr/bin/python
-#
+#!/usr/bin/env python
 # Copyright (c) 2011 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 sys
 
 # Note: some of these files are imported to register cmdline options.
 from idl_generator import Generator
 from idl_option import ParseOptions
 from idl_outfile import IDLOutFile
 from idl_parser import ParseFiles
 from idl_c_header import HGen
 from idl_gen_pnacl import PnaclGen
 
 
-def Main(args):
+def Main():
+  args = sys.argv[1:]
+  # If no arguments are provided, assume we are tring to rebuild the
+  # C headers with warnings off.
+  if not args:
+    args = ['--wnone', '--cgen', '--range=start,end']
+
   filenames = ParseOptions(args)
   ast = ParseFiles(filenames)
   return Generator.Run(ast)
 
+
 if __name__ == '__main__':
-  args = sys.argv[1:]
-
-  # If no arguments are provided, assume we are tring to rebuild the
-  # C headers with warnings off.
-  if not args: args = ['--wnone', '--cgen', '--range=start,end']
-
-  sys.exit(Main(args))
+  sys.exit(Main())