Merge "Prevent exfiltration of system files via avatar picker." into tm-dev am: 5489aa36

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



Change-Id: I6ecc86032e6871d6e2cec55b61533121c1567daf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>