Merge "Prevent exfiltration of system files via avatar picker." into tm-dev am: 5489aa365f am: 33a08e907c am: 9a62860abe

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19754655

Change-Id: I056096b4afcf56b5bfc936bd80c65e26239ea820
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>