let picture record take a bbh directly

I'm not sure I see a compelling reason for BBH factory objects
to exist, as opposed to say, factory functions.  I don't see any
major harm in letting people hold onto BBH objects themselves.

This allows the caller to create and hang onto the BBH themselves,
allowing use cases like the slight extension I've made to the unit
test PictureNegativeSpace as a demo.  Not super useful yet, as
SkBBoxHierarchy is not a public type...

And add test that mini pictures fill the bbh, which had never been
an interesting question until now we let the user hold onto the BBH.

Bug: skia:9796
Change-Id: I14737f25b31a457a8716669183af0c3bbf01859b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/265445
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
4 files changed