Extensions Docs Server: Use X-Frame-Options to prevent clickjacking

I'm not quite sure how to test this, but the header is set.

BUG=146017


Review URL: https://chromiumcodereview.appspot.com/10905051

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@154858 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed