[automerger skipped] Add android:exported tag am: 2fe8554eae -s ours

am skip reason: Merged-In Icf7492e392cf20986990be2752e6357d4cdb352c with SHA-1 c61b39439e is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/developers/samples/android/+/15828964

Change-Id: I5a798959c8bd28746b91dfcf3a0c93c1bccbe5b5