Merge "Add a button for floating tasks to taskbar (behind a flag)" into tm-qpr-dev am: 13b7e00fff

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/19874561

Change-Id: Ic1c92bac2b98e3eac04acd567ab208f814f00408
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>