Fixes crash in adding a menu item. As far as I can tell l10n_util::GetString(IDS_TASK_MANAGER) is returning "". Tony, myself and Rahul don't think this should be possible, yet we have crashes indicating otherwise. If IDS_TASK_MANAGER returns an emtpy string then menu derefs NULL and we crash.
Fixes crash in adding a menu item. As far as I can tell
l10n_util::GetString(IDS_TASK_MANAGER) is returning "". Tony, myself
and Rahul don't think this should be possible, yet we have crashes
indicating otherwise. If IDS_TASK_MANAGER returns an emtpy string then
menu derefs NULL and we crash.

BUG=6206
TEST=no way to directly test this, instead just make sure menus still
     work.

Review URL: http://codereview.chromium.org/19434

git-svn-id: http://src.chromium.org/svn/trunk/src@8829 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 450aa99cb93871f1ae4d5428ecc0058c009766f2
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