Remove wrapping of mojo::Callbacks in std::unique_ptr.

Remove wrapping of mojo::Callbacks in std::unique_ptr.

This wrapping was added in r355704 because at the time mojo::Callbacks
did not like being freed on arbitrary threads, which would happen if
they were passed to //device/usb APIs. This is no longer an issue so the
wrapping can be removed.

BUG=None

Committed: https://crrev.com/c2dc1ac6393b162be226c84438ec4a39cef7d558
Cr-Commit-Position: refs/heads/master@{#412582}

[Reilly Grant (use Gerrit), 2016-08-10 20:23:32]

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

[Reilly Grant (use Gerrit), 2016-08-10 20:23:48]

reillyg@chromium.org changed reviewers:
+ rockot@chromium.org

[Reilly Grant (use Gerrit), 2016-08-10 20:23:50]

PTAL, it looks like this hasn't broken anything.

[commit-bot: I haz the power, 2016-08-10 20:24:07]

Dry run: 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, 2016-08-10 21:43:31]

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

[commit-bot: I haz the power, 2016-08-10 21:43:32]

Dry run: This issue passed the CQ dry run.

[Ken Rockot(use gerrit already), 2016-08-17 14:51:39]

lgtm

[Reilly Grant (use Gerrit), 2016-08-17 17:01:38]

Rebased.

[Reilly Grant (use Gerrit), 2016-08-17 17:02:23]

The CQ bit was checked by reillyg@chromium.org

[Reilly Grant (use Gerrit), 2016-08-17 17:02:23]

The patchset sent to the CQ was uploaded after l-g-t-m from rockot@chromium.org
Link to the patchset: https://codereview.chromium.org/2236683002/#ps20001
(title: "Rebased.")

[commit-bot: I haz the power, 2016-08-17 17:02:47]

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, 2016-08-17 17:59:05]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-08-17 18:06:09]

Description was changed from

==========
Remove wrapping of mojo::Callbacks in std::unique_ptr.

This wrapping was added in r355704 because at the time mojo::Callbacks
did not like being freed on arbitrary threads, which would happen if
they were passed to //device/usb APIs. This is no longer an issue so the
wrapping can be removed.

BUG=None
==========

to

==========
Remove wrapping of mojo::Callbacks in std::unique_ptr.

This wrapping was added in r355704 because at the time mojo::Callbacks
did not like being freed on arbitrary threads, which would happen if
they were passed to //device/usb APIs. This is no longer an issue so the
wrapping can be removed.

BUG=None

Committed: https://crrev.com/c2dc1ac6393b162be226c84438ec4a39cef7d558
Cr-Commit-Position: refs/heads/master@{#412582}
==========

[commit-bot: I haz the power, 2016-08-17 18:06:10]

Patchset 2 (id:??) landed as
https://crrev.com/c2dc1ac6393b162be226c84438ec4a39cef7d558
Cr-Commit-Position: refs/heads/master@{#412582}