Fix docs/callback.md style

Fix docs/callback.md style

* Add document title
* Fix line wrapping

Committed: https://crrev.com/a431351621c601eec00f501a6476cdfe6b71f724
Cr-Commit-Position: refs/heads/master@{#416597}

[tzik, 2016-09-05 07:35:32]

Patchset #1 (id:1) has been deleted

[tzik, 2016-09-05 07:35:39]

Description was changed from

==========
Fix docs/callback.md style

BUG=
==========

to

==========
Fix docs/callback.md style

* Add document title
* Fix line wrapping
==========

[tzik, 2016-09-05 07:37:54]

tzik@chromium.org changed reviewers:
+ yutak@chromium.org

[tzik, 2016-09-05 07:37:55]

PTAL

[Yuta Kitamura, 2016-09-05 07:40:52]

lgtm

[tzik, 2016-09-06 06:15:28]

The CQ bit was checked by tzik@chromium.org

[commit-bot: I haz the power, 2016-09-06 06:15:41]

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 06:51:29]

Description was changed from

==========
Fix docs/callback.md style

* Add document title
* Fix line wrapping
==========

to

==========
Fix docs/callback.md style

* Add document title
* Fix line wrapping
==========

[commit-bot: I haz the power, 2016-09-06 06:51:30]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2016-09-06 06:52:57]

Description was changed from

==========
Fix docs/callback.md style

* Add document title
* Fix line wrapping
==========

to

==========
Fix docs/callback.md style

* Add document title
* Fix line wrapping

Committed: https://crrev.com/a431351621c601eec00f501a6476cdfe6b71f724
Cr-Commit-Position: refs/heads/master@{#416597}
==========

[commit-bot: I haz the power, 2016-09-06 06:52:57]

Patchset 1 (id:??) landed as
https://crrev.com/a431351621c601eec00f501a6476cdfe6b71f724
Cr-Commit-Position: refs/heads/master@{#416597}