Speak spoken feedback announcements earlier before sending notifications.

BUG=305728
TEST=Verify (via ctrl+alt+z) spoken feedback announcements occur on login screen (m30).

Review URL: https://codereview.chromium.org/26765003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227968 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227968