Remove calls to MessageLoop::current() in sync.

Remove calls to MessageLoop::current() in sync.

Why?
The fact that there's a MessageLoop on the thread is an
unnecessary implementation detail. When browser threads
are migrated to base/task_scheduler, tasks will no longer
have access to a MessageLoop.

These changes were generated manually.

BUG=616447
R=maxbogue@chromium.org

Committed: https://crrev.com/f7ca8b710dcd9f45e852ceea546b5de96e8d7ca3
Cr-Commit-Position: refs/heads/master@{#400983}

[maxbogue, 2016-06-21 02:40:18]

lgtm

[fdoray, 2016-06-21 12:59:22]

The CQ bit was checked by fdoray@chromium.org

[fdoray, 2016-06-21 12:59:22]

The patchset sent to the CQ was uploaded after l-g-t-m from
maxbogue@chromium.org
Link to the patchset: https://codereview.chromium.org/2083713002/#ps20001
(title: "self-review")

[commit-bot: I haz the power, 2016-06-21 12:59:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2083713002/20001

[commit-bot: I haz the power, 2016-06-21 14:00:45]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-21 14:02:31]

Description was changed from

==========
Remove calls to MessageLoop::current() in sync.

Why?
The fact that there's a MessageLoop on the thread is an
unnecessary implementation detail. When browser threads
are migrated to base/task_scheduler, tasks will no longer
have access to a MessageLoop.

These changes were generated manually.

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

to

==========
Remove calls to MessageLoop::current() in sync.

Why?
The fact that there's a MessageLoop on the thread is an
unnecessary implementation detail. When browser threads
are migrated to base/task_scheduler, tasks will no longer
have access to a MessageLoop.

These changes were generated manually.

BUG=616447
R=maxbogue@chromium.org

Committed: https://crrev.com/f7ca8b710dcd9f45e852ceea546b5de96e8d7ca3
Cr-Commit-Position: refs/heads/master@{#400983}
==========

[commit-bot: I haz the power, 2016-06-21 14:02:31]

Patchset 2 (id:??) landed as
https://crrev.com/f7ca8b710dcd9f45e852ceea546b5de96e8d7ca3
Cr-Commit-Position: refs/heads/master@{#400983}