[automerger skipped] [DO NOT MERGE] Make PendingIntents in screenshots immutable am: 16560709 am: 6867761f -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13950909

Change-Id: I39fe228732d697cfe65caadaf52bbafcc92a54ef