sync: Point dev channel sync engines to clients4.google.com/chrome-sync/dev
sync: Point dev channel sync engines to clients4.google.com/chrome-sync/dev

BUG=none
TEST=create unofficial build or build with version string modifier equal to "dev".
start syncing.


Review URL: http://codereview.chromium.org/2847006

git-svn-id: http://src.chromium.org/svn/trunk/src@49865 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 6452bc049319d6cddf1a45017e4e4dfc8ce24496
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