ui: Turn on slimming paint by default with impl-side painting.

ui: Turn on slimming paint by default with impl-side painting.

Slimming paint is now much faster than PicturePile backed recording
for impl-side painting. It's what we're going to ship when we enable
impl-side, so make it the default. Left the disable switch just in case
to try out PicturePile if we need to for some reason until we turn
on impl-side by default.

R=piman@chromium.org, sky
BUG=466426
Committed: https://crrev.com/7d4e7af2da84344d04553fd7e913189ca396ddc3
Cr-Commit-Position: refs/heads/master@{#329469}

[danakj, 2015-05-12 17:58:18]

This changes no default behaviour as impl-side painting is still behind a flag.

[piman, 2015-05-12 19:21:01]

lgtm

[sky, 2015-05-12 19:38:03]

LGTM

[danakj, 2015-05-12 19:54:04]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2015-05-12 19:54:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1141583003/1

[commit-bot: I haz the power, 2015-05-12 20:01:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-12 20:02:25]

Patchset 1 (id:??) landed as
https://crrev.com/7d4e7af2da84344d04553fd7e913189ca396ddc3
Cr-Commit-Position: refs/heads/master@{#329469}