Turn on DNS prefetching.
Turn on DNS prefetching.

Review URL: http://codereview.chromium.org/21281

git-svn-id: http://src.chromium.org/svn/trunk/src@10025 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 730027af9052a5d76afcd28c83b2b3248ac4186c
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser