Added string for extensions sync.
Added string for extensions sync.

BUG=32413
TEST=trybots

Review URL: http://codereview.chromium.org/2724004

git-svn-id: http://src.chromium.org/svn/trunk/src@49199 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: ffc4094085b8baac53ce6c26b924afed9442033c
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