[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: 0245e885 am: ea7e6b49 -s ours

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

Change-Id: Ifb018971f35898215072af617670adacb36b6ad0