[ Merge of http://go/wvgerrit/15474 ]
Changes to releaseAllSecureStops made use of a session that was
initialized only if getSecureStops had been previously called. If it was not,
accessing the session resulted in a segfault. This was uncovered by a change
in how the Netflix app invoked mediaDrm.
b/23498809
Change-Id: Ib426ae1830c3a42c5e0849f1b6e8bbfe0d2c74ff
25a6185c84