Fix a segfault in DeleteNotifications test caused by an invalid C-cast.
Fix a segfault in DeleteNotifications test caused by an invalid C-cast.

Re-enable the test.

BUG=49799
TEST=TopSitesTest::DeleteNotifications.

Review URL: http://codereview.chromium.org/2847066

git-svn-id: http://src.chromium.org/svn/trunk/src@53372 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: bb9e127741942b1282ad32db86637957d63476d6
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