Replace MessageLoopProxy usage with ThreadTaskRunnerHandle in net/socket/ module.

Replace MessageLoopProxy usage with ThreadTaskRunnerHandle in net/socket/ module.

MessageLoopProxy is deprecated.
This basically does search and replace of:

MessageLoopProxy::current() -> ThreadTaskRunnerHandle::Get().

BUG=391045
Committed: https://crrev.com/30444467d4d5d3e7e1489df1d5c2febfe307e0d4
Cr-Commit-Position: refs/heads/master@{#328248}

[payal.pandey, 2015-05-04 11:14:45]

payal.pandey@samsung.com changed reviewers:
+ eroman@chromium.org

[payal.pandey, 2015-05-04 11:14:46]

Please have a look, Thanks.

[eroman, 2015-05-04 21:49:43]

lgtm

[payal.pandey, 2015-05-05 00:58:30]

The CQ bit was checked by payal.pandey@samsung.com

[commit-bot: I haz the power, 2015-05-05 00:59:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1126553002/1

[commit-bot: I haz the power, 2015-05-05 01:35:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-05 01:36:43]

Patchset 1 (id:??) landed as
https://crrev.com/30444467d4d5d3e7e1489df1d5c2febfe307e0d4
Cr-Commit-Position: refs/heads/master@{#328248}