Remove calls to deprecated MessageLoop methods in content.

Remove calls to deprecated MessageLoop methods in content.

This CL (hopefully) removes all calls to these methods in content:
- MessageLoop::PostTask
- MessageLoop::PostDelayedTask
- MessageLoop::DeleteSoon
- MessageLoop::ReleaseSoon
- MessageLoop::Run
- MessageLoop::RunUntilIdle

BUG=616447
R=avi@chromium.org

Committed: https://crrev.com/4ae151ac5827e72f0c8e7f5730f77e2a466ae4d9
Cr-Commit-Position: refs/heads/master@{#416734}

[fdoray, 2016-09-06 20:23:50]

The CQ bit was checked by fdoray@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-06 20:24:19]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[fdoray, 2016-09-06 20:56:39]

PTAL

[commit-bot: I haz the power, 2016-09-06 21:13:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-06 21:13:50]

Dry run: This issue passed the CQ dry run.

[Avi (use Gerrit), 2016-09-06 21:24:42]

lgtm

stampity stamp

[fdoray, 2016-09-06 21:29:54]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2016-09-06 21:30:24]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-06 21:35:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-06 21:38:43]

Description was changed from

==========
Remove calls to deprecated MessageLoop methods in content.

This CL (hopefully) removes all calls to these methods in content:
- MessageLoop::PostTask
- MessageLoop::PostDelayedTask
- MessageLoop::DeleteSoon
- MessageLoop::ReleaseSoon
- MessageLoop::Run
- MessageLoop::RunUntilIdle

BUG=616447
R=avi@chromium.org
==========

to

==========
Remove calls to deprecated MessageLoop methods in content.

This CL (hopefully) removes all calls to these methods in content:
- MessageLoop::PostTask
- MessageLoop::PostDelayedTask
- MessageLoop::DeleteSoon
- MessageLoop::ReleaseSoon
- MessageLoop::Run
- MessageLoop::RunUntilIdle

BUG=616447
R=avi@chromium.org

Committed: https://crrev.com/4ae151ac5827e72f0c8e7f5730f77e2a466ae4d9
Cr-Commit-Position: refs/heads/master@{#416734}
==========

[commit-bot: I haz the power, 2016-09-06 21:38:44]

Patchset 1 (id:??) landed as
https://crrev.com/4ae151ac5827e72f0c8e7f5730f77e2a466ae4d9
Cr-Commit-Position: refs/heads/master@{#416734}