[automerger skipped] [RESTRICT AUTOMERGE] Fix UAF in clearkey service's...

[automerger skipped] [RESTRICT AUTOMERGE] Fix UAF in clearkey service's MemoryFileSystem am: 9ba33b35 -s ours am: 0a2abba4 -s ours am: a4e3bea9 am: cc0a8fc9 -s ours am: 8b77104c -s ours

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Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/13711823

Change-Id: I9d37daac99d2c5e798d11d39318cc8b77fefe573