base

Avoid ref-ing AndroidPixelRefs that wrap others in globalRef/Unref

bug:10691404

Only ref the wrapped pixel refs, so that they are the single source of
correct refcount, since the wrapping pixel ref can change out from
underneath an SkBitmap.

Change-Id: I253b8737d2afdcc567a26725fa40b1d9ef0e6a92