[androidkit] Simple animation demo

Oscillating rect demo using a dedicated render thread.

At the moment this is using an intermediate Bitmap for rendering, but
should be converted to native GL Surface when it becomes available.

TBR=
Change-Id: I9b4f66598b6d2b56e865e7f1d10139a2bcf1f3e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/398536
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Florin Malita <fmalita@google.com>
3 files changed