Add strings for extension / sync promos.
Add strings for extension / sync promos.

Review URL: http://codereview.chromium.org/371094

git-svn-id: http://src.chromium.org/svn/trunk/src@31541 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: db20cc865ab92e9830660a3f23ad52fabadbbe56
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