cc: Move soon bin apron from tile manager to tiling.
We split our tiles into several regions: now, soon, eventually, among
others. Now tiles are tiles that are within the visible rect. Soon
tiles are close prepaint tiles (such as tiles coming from the
skewport). Eventually tiles are far away prepaint tiles. Since the
skewport is calculated using finite differences, the first time
visible rect moves, we might not have content prepainted. As a solution,
we put in a "backfling guard", a constant distance away from the
viewport where we promote tiles from eventually to soon.
This patch moves this guard from being a distance check in tile manager
to being an explicit region in the tiling.
R=enne
Review URL: https://codereview.chromium.org/
271733003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269157 0039d316-1c4b-4281-b951-d872f2087c98