base

Enable changing properties of layer paint

Previously, to draw a layered view with a changed Paint object for the
drawLayer operation, you'd have to invalidate the parent view, to get the
native DisplayList to pick up the new Paint properties. This change adds
API and functionality so that the developer can call setLayerPaint(), which
does the proper invalidation (lightweight, doesn't cause redrawing the view).

Issue #6923810 Make it easy to efficiently animate a layer's Paint

Change-Id: I7fea79788d50f6d9c86dd5e5b2a4490cb95142bb