chromeos: Use a PaintRecorder to access the Canvas for painting.

chromeos: Use a PaintRecorder to access the Canvas for painting.

Don't use the canvas() from the PaintContext so that we can have the
PaintContext be backed by a DisplayItemList instead in the future.
Access to the Canvas should be done through a PaintRecorder.

R=oshima
BUG=466426
Committed: https://crrev.com/a91b108ddfd16dcd539008917ea56d89cb7744cb
Cr-Commit-Position: refs/heads/master@{#324115}

[oshima, 2015-04-07 20:32:02]

lgtm

[danakj, 2015-04-07 20:43:58]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2015-04-07 20:44:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1066113002/1

[commit-bot: I haz the power, 2015-04-07 20:59:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-07 21:00:22]

Patchset 1 (id:??) landed as
https://crrev.com/a91b108ddfd16dcd539008917ea56d89cb7744cb
Cr-Commit-Position: refs/heads/master@{#324115}