Keep weak reference to parent context in TintResources

Avoids a framework issue on API <= 23 whereby the resources are
incorrectly cached in the constant state of preloaded
DrawableContainers when newDrawable(Resources) is called.

Bug: 27477801
Change-Id: I28f8a76687aff5c7ca9275d1e6cc46a553193ab6
1 file changed