[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

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

Change-Id: I2ec3159aa92a2c1ebbc0545d11c86968f219bd0b