Delete ThreadChecker from FontAtlas.

Delete ThreadChecker from FontAtlas.

This object is created on the main thread and used on the impl thread.

BUG=160312
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=167057

[aelias_OOO_until_Jul13, 2012-11-10 00:50:42]

Hi, fix for the DCHECK failure.

[jamesr, 2012-11-10 00:56:03]

On 2012/11/10 00:50:42, aelias wrote:
> Hi, fix for the DCHECK failure.

Even better would be calling DetachFromThread() when we hand this over to the
impl thread so the checker can still make sure all uses after creation are on
the same thread.

lgtm

[aelias_OOO_until_Jul13, 2012-11-10 01:05:51]

I'll keep that in mind; that may be a good approach to take with other classes. 
For this debug feature class, though, I think it would amount to unnecessary
boilerplate and I'd rather delete it.

[commit-bot: I haz the power, 2012-11-10 01:06:11]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/aelias@chromium.org/11360178/1

[jamesr, 2012-11-10 01:56:01]

On 2012/11/10 01:05:51, aelias wrote:
> I'll keep that in mind; that may be a good approach to take with other
classes. 
> For this debug feature class, though, I think it would amount to unnecessary
> boilerplate and I'd rather delete it.

Works for me

[commit-bot: I haz the power, 2012-11-10 04:17:20]

Change committed as 167057