Fix broken threading model in CheckDesktopNotificationPermission
Over time, this function (which is called on the IO thread) was updated
to use DesktopNotificationService. While the methods in that service
were enforced to run on the correct thread, it's not possible to get
the notification service from the ProfileIOData safely. This removes the
dependency on DesktopNotificationService from the IO-thread notification
functions.
BUG=256638
Review URL: https://codereview.chromium.org/
61323002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234886 0039d316-1c4b-4281-b951-d872f2087c98