Move pyauto extensions.py expected files to data dir.

This is a small change to expect the directory of extensions and the urls file to be in the data directory instead of the current directory.

Review URL: http://codereview.chromium.org/3067028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@54779 0039d316-1c4b-4281-b951-d872f2087c98