Handle padding in wrap content

This CL fixes a bug in GridLayoutManager and StaggeredGridLM where
they were ignoring padding in non-scroll direction when calculating
the content wrapping. This would eventually cause clipped children.

I've also fixed some code-style errors.

Change-Id: I7dca4a30007596ae52bf367e5f7af9a10e387954
Bug: 26769843
7 files changed