[Android WebView] Whitelist Python license

Python license lets one to distribute a modified version
without making ones changes open source.

TBR=boliu@chromium.org

Review URL: https://codereview.chromium.org/117203003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242371 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242371