[ Merge of http://go/wvgerrit/119684 ]
This allows for a default DRM certificate that includes an expiration
time and a legacy one without for each app+origin specific identifier.
Existing offline licenses/secure stops are not associated with a
certificate, and so we cannot delete legacy certificates even after
fetching a new one. New offline licenses/secure stops will be associated
with certificate information, so we will not have this problem going
forward.
Bug: 169740403
Test: WV unit/integration tests
Change-Id: I0f08f6bf98775fd43927243dc4a9f75f21bfbbcc
3b15087627