Merge "VirtualDisplayTaskEmbedder: Post background color change callback" into rvc-dev am: 5c53f0af8b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11726785

Change-Id: I19903b4a4acafb3e7824dffc0c4a429d950f6f51