[automerger skipped] [DO NOT MERGE] Make GlobalScreenshot PendingIntents immutable am: f4eefc55 am: 4cccd0c4 -s ours am: 67bd3cae am: 3ce491fe -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12773073

Change-Id: Idd3b3c94a07a52a5ce3d2b5974f5097c909a66e1