Hide taskbar content while dreaming. am: f0f94f2ed9 am: 472fe81e62

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/22387402

Change-Id: Ib3d617628644087d9db762562506d1a429e29636
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>