[cros] Make sure that sync service is not accessed when loading pages before user has signed in.
[cros] Make sure that sync service is not accessed when loading pages before user has signed in.

BUG=chromium-os:10437
TEST=Manual

Review URL: http://codereview.chromium.org/5984004

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@69853 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser