Fix python scripts in src/chrome/

chrome/test/pyautolib/fetch_prebuilt_pyauto.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.
 
 """Fetch prebuilt binaries to run PyAuto.
 
 Sets up Chrome and PyAuto binaries using prebuilt binaries from the
 continuous build archives.  Works on mac, win, linux (32 & 64 bit).
 
 Examples:
@@ skipping 152 matching lines @@
       os.chdir(self._outdir)
       framework = glob.glob(os.path.join(
           mac_app_name, 'Contents', 'Versions', '*', '*.framework'))[0]
       print framework
       dest = os.path.basename(framework)
       os.path.lexists(dest) and os.remove(dest)
       print 'Creating symlink "%s"' % dest
       os.symlink(framework, dest)
 
     print 'Prepared binaries in "%s"' % self._outdir
+    return 0
 
 
 if __name__ == '__main__':
-  FetchPrebuilt().Run()
+  sys.exit(FetchPrebuilt().Run())