[automerger skipped] [DO NOT MERGE] Make GlobalScreenshot PendingIntents immutable am: bb4bfcc5 -s ours am: 57f5463b am: 5f3cb8f6 am: 175ddeb9 am: 7b439e29 -s ours

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Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12770654

Change-Id: Ia095c3445a461f7e9fb0588acb26261746d6bb27