Merge "Revert "Extract assistant logic from NavigationBar to share with Taskbar"" into sc-v2-dev am: f730a2c592 am: f9cf13f77a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16331846

Change-Id: I122c70bde49e58f3f66cddee9e1fabe562357153