Merge "Mark implicit PendingIntents as immutable am: 599c3e4b am: fa64ffd0...

Merge "Mark implicit PendingIntents as immutable am: 599c3e4b am: fa64ffd0 am: 3ff2a5cb am: ec741cf6 am: 90584938" into rvc-qpr-dev-plus-aosp am: 378b27d2

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12296405

Change-Id: Ic32247d81c526c3b106312ad22e599c79e85b3bf