Fix unbalanced add/remove task observer

Fix unbalanced add/remove task observer

BUG=

Committed: https://crrev.com/6dfe493ac5735717b5125435db61c57fa2ff5922
Cr-Commit-Position: refs/heads/master@{#418814}

[alex clarke (OOO till 29th), 2016-09-14 16:08:30]

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

[commit-bot: I haz the power, 2016-09-14 16:08:44]

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, 2016-09-14 17:44:29]

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

[commit-bot: I haz the power, 2016-09-14 17:44:30]

Dry run: This issue passed the CQ dry run.

[alex clarke (OOO till 29th), 2016-09-15 08:58:58]

alexclarke@chromium.org changed reviewers:
+ jochen@chromium.org

[alex clarke (OOO till 29th), 2016-09-15 08:58:59]

PTAL

[jochen (gone - plz use gerrit), 2016-09-15 09:27:41]

lgtm

[alex clarke (OOO till 29th), 2016-09-15 09:30:31]

The CQ bit was checked by alexclarke@chromium.org

[commit-bot: I haz the power, 2016-09-15 09:30:49]

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, 2016-09-15 09:37:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-15 09:40:46]

Description was changed from

==========
Fix unbalanced add/remove task observer

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

to

==========
Fix unbalanced add/remove task observer

BUG=

Committed: https://crrev.com/6dfe493ac5735717b5125435db61c57fa2ff5922
Cr-Commit-Position: refs/heads/master@{#418814}
==========

[commit-bot: I haz the power, 2016-09-15 09:40:48]

Patchset 1 (id:??) landed as
https://crrev.com/6dfe493ac5735717b5125435db61c57fa2ff5922
Cr-Commit-Position: refs/heads/master@{#418814}