Merge "Update split screen divider to match new taskbar color" into sc-v2-dev am: 16bd3c23c4 am: 9d4f8fc611

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15898640

Change-Id: I3089ccd1b128db36ab7c6718ee702913937b3027