[ Merge of http://go/wvgerrit/74343 ]
This replicates a Netflix test that adds secure stops and removes them
one at a time, while some of the sessions are still open. Usage
enties will be deleted at the time, but the usage header table
will not be shrunk if the last entry is in use. This happens later when
sessions are closed and the last usage entry is no longer in use.
Bug: 120894148
Test: WV unit/integration tests, CE CDM tests
Change-Id: Ib572950afc61754fe5f3c417e650d5d08503425a
8942f7682a