Don't layout twice in ui::Compositor

Don't layout twice in ui::Compositor

In the SingleThreadProxy+SchedulerClient patch,
LayerTreeHostClient::Layout is now called via DoCommit which is called
via Composite(Immediately).  In no cases should the embedder call
Layout() manually.

R=danakj@chromium.org,piman@chromium.org
BUG=none

Committed: https://crrev.com/3115a3df298d733cb36306b351a00f55f8452214
Cr-Commit-Position: refs/heads/master@{#293632}

[enne (OOO), 2014-09-05 23:34:50]

OOPS

I forgot to remove this when I remove the ui::Compositor changes from my
SchedulerClient patch.

[danakj, 2014-09-05 23:45:25]

On 2014/09/05 23:34:50, enne_OOO_until_sep_22 wrote:
> OOPS
> 
> I forgot to remove this when I remove the ui::Compositor changes from my
> SchedulerClient patch.

LGTM

[piman, 2014-09-06 01:16:00]

oops.
LGTM

[enne (OOO), 2014-09-06 06:52:44]

The CQ bit was checked by enne@chromium.org

[commit-bot: I haz the power, 2014-09-06 06:53:49]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/enne@chromium.org/545343003/1

[commit-bot: I haz the power, 2014-09-06 08:56:32]

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

[commit-bot: I haz the power, 2014-09-06 08:56:33]

Exceeded time limit waiting for builds to trigger.

[danakj, 2014-09-06 19:27:38]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2014-09-06 19:28:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/enne@chromium.org/545343003/1

[commit-bot: I haz the power, 2014-09-06 20:06:23]

Committed patchset #1 (id:1) as 29294cf3d94b22a104ccd8b4e7a3799c18808a99

[commit-bot: I haz the power, 2014-09-10 03:43:16]

Patchset 1 (id:??) landed as
https://crrev.com/3115a3df298d733cb36306b351a00f55f8452214
Cr-Commit-Position: refs/heads/master@{#293632}