Merge "free weakref to linearblock when it is destroy" am: a4f4128f10 am: fe121d44ee

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1538181

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I80e6dd83b811fca6512ca70bfb0520f40a0bf73b