Replaced DCHECK with CHECK to detect invalid socket usage.

Replaced DCHECK with CHECK to detect invalid socket usage.
Issue like 121085 or 320427 could be caused by writing request on busy sockets.

BUG=121085
Committed: https://crrev.com/63b47546afb414f9e62a9a64518a92c5aeb0ce63
Cr-Commit-Position: refs/heads/master@{#297195}

[Vitaly Buka (NO REVIEWS), 2014-09-24 22:12:40]

vitalybuka@chromium.org changed reviewers:
+ rch@chromium.org

[Vitaly Buka (NO REVIEWS), 2014-09-24 22:13:00]

same as https://codereview.chromium.org/580163003/ for TCP sockets

[Ryan Hamilton, 2014-09-26 03:27:09]

lgtm

[Vitaly Buka (NO REVIEWS), 2014-09-26 04:04:16]

The CQ bit was checked by vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2014-09-26 04:04:18]

The CQ bit was unchecked by vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2014-09-26 04:05:06]

On 2014/09/26 03:27:09, Ryan Hamilton wrote:
> lgtm

thanks. I'll wait to commit after branch.

[Vitaly Buka (NO REVIEWS), 2014-09-29 17:09:30]

The CQ bit was checked by vitalybuka@chromium.org

[commit-bot: I haz the power, 2014-09-29 17:09:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/603783002/1

[commit-bot: I haz the power, 2014-09-29 17:14:26]

Committed patchset #1 (id:1) as 1399bdcc01a895e874835f60549ad5e963862363

[commit-bot: I haz the power, 2014-09-29 17:15:43]

Patchset 1 (id:??) landed as
https://crrev.com/63b47546afb414f9e62a9a64518a92c5aeb0ce63
Cr-Commit-Position: refs/heads/master@{#297195}