Uses WeakPtrFactory instead of base::Unretained.

Uses WeakPtrFactory instead of base::Unretained.

Although TrayIME removes the notification, the callback notification
delegate may survive due to complicated ref-counted-ness of
NotificationDelegate.

Anyways WeakPtr would be better here rather than Unretained.

BUG=336650
R=stevenjb@chromium.org, dewittj@chromium.org
TEST=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=248577

[stevenjb, 2014-02-03 18:11:36]

lgtm

[dewittj, 2014-02-03 18:11:58]

Did you find a reproducible way to cause the crash, or is this speculative?

lgtm

[Jun Mukai, 2014-02-03 18:49:05]

On 2014/02/03 18:11:58, dewittj wrote:
> Did you find a reproducible way to cause the crash, or is this speculative?
> 
> lgtm

Just speculative...

[Jun Mukai, 2014-02-03 18:49:17]

The CQ bit was checked by mukai@chromium.org

[commit-bot: I haz the power, 2014-02-03 18:50:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mukai@chromium.org/138833004/1

[commit-bot: I haz the power, 2014-02-03 21:27:27]

Change committed as 248577

[commit-bot: I haz the power, 2014-02-03 21:27:32]

CQ bit was unchecked on CL. Ignoring.

[commit-bot: I haz the power, 2014-02-03 21:27:36]

CQ bit was unchecked on CL. Ignoring.