Fix crash when removing all notifications by "Clear all" button.

Fix crash when removing all notifications by "Clear all" button.

BUG=701348
Review-Url: https://codereview.chromium.org/2750853005
Cr-Commit-Position: refs/heads/master@{#457005}
Committed: https://chromium.googlesource.com/chromium/src/+/9f177cc7d313503e07a143337105868ef182022b

[yhanada, 2017-03-15 05:12:18]

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

[commit-bot: I haz the power, 2017-03-15 05:12:31]

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

[yhanada, 2017-03-15 05:15:40]

yhanada@chromium.org changed reviewers:
+ yoshiki@chromium.org

[yhanada, 2017-03-15 05:15:40]

PTAL.

[yoshiki, 2017-03-15 05:16:20]

lgtm

Thanks!

[commit-bot: I haz the power, 2017-03-15 05:56:07]

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

[commit-bot: I haz the power, 2017-03-15 05:56:08]

Dry run: This issue passed the CQ dry run.

[yhanada, 2017-03-15 05:57:54]

The CQ bit was checked by yhanada@chromium.org

[commit-bot: I haz the power, 2017-03-15 05:58:07]

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, 2017-03-15 06:03:15]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489557474212080, "parent_rev":
"b8a31c8731d21407c7db6a8a5a9bf01ace20ab5f", "commit_rev":
"9f177cc7d313503e07a143337105868ef182022b"}

[commit-bot: I haz the power, 2017-03-15 06:04:13]

Description was changed from

==========
Fix crash when removing all notifications by "Clear all" button.

BUG=701348
==========

to

==========
Fix crash when removing all notifications by "Clear all" button.

BUG=701348

Review-Url: https://codereview.chromium.org/2750853005
Cr-Commit-Position: refs/heads/master@{#457005}
Committed:
https://chromium.googlesource.com/chromium/src/+/9f177cc7d313503e07a143337105...
==========

[commit-bot: I haz the power, 2017-03-15 06:04:14]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/9f177cc7d313503e07a143337105...