Add more WeakPtr checks for SurfaceFactory in SurfaceAggregator.

Add more WeakPtr checks for SurfaceFactory in SurfaceAggregator.

With DestroyOnSequence, a Surface can live long after its SurfaceFactory dies, so every use of the SurfaceFactory needs to check whether it still exists.

Committed: https://crrev.com/84c27fac01d5cb35c80abf59cf3b6f2ecbf2fc22
Cr-Commit-Position: refs/heads/master@{#301572}

[jbauman, 2014-10-28 01:55:24]

jbauman@chromium.org changed reviewers:
+ jamesr@chromium.org

[jamesr, 2014-10-28 04:56:00]

lgtm

[jbauman, 2014-10-28 05:08:14]

The CQ bit was checked by jbauman@chromium.org

[commit-bot: I haz the power, 2014-10-28 05:08:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/683623003/1

[commit-bot: I haz the power, 2014-10-28 06:07:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-28 06:08:28]

Patchset 1 (id:??) landed as
https://crrev.com/84c27fac01d5cb35c80abf59cf3b6f2ecbf2fc22
Cr-Commit-Position: refs/heads/master@{#301572}