Reduce tile memory size

One tile memory takes 160 bytes currently.
This patch can reduce the tile memory by removing unnecessary
variables and packing the booleans to 144 bytes.

BUG=341919

Review URL: https://codereview.chromium.org/810713002

Cr-Commit-Position: refs/heads/master@{#309504}
2 files changed