cc: Add CHECKs that the backing size reported by canvas matches.

cc: Add CHECKs that the backing size reported by canvas matches.

After making the canvas, ensure the size it reports is correct. Also
pass the full content_rect to ContentLayerUpdater::PaintContents
instead of deriving the size from the canvas, and double-check the
size matches the canvas there.

R=reveman@chromium.org
BUG=358470
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=261526

[enne (OOO), 2014-04-02 17:37:50]

landmines lgtm

[reveman, 2014-04-02 17:42:27]

lgtm

[danakj, 2014-04-03 17:06:37]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2014-04-03 17:06:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/222573002/1

[commit-bot: I haz the power, 2014-04-03 20:50:56]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 20:50:56]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[danakj, 2014-04-03 21:00:45]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2014-04-03 21:02:47]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/222573002/1

[commit-bot: I haz the power, 2014-04-03 21:05:33]

Change committed as 261526