[ Merge of http://go/wvgerrit/120508 ]
Offline licenses will now store the DRM certificate information. This
allows for expired certificates to be deleted and replaced without
losing the ability to use offline licenses.
Bug: 169740403
Test: WV unit/integration tests
DeviceFilesTest.RetrieveLicenses
DeviceFilesTest.StoreLicenses
Change-Id: Ic0de6328d32e0000d1b58c81019e6c2227278cc4
57ebb70fe7