DevTools Timeline: fix NPE when collapsing the last group

DevTools Timeline: fix NPE when collapsing the last group

... when selection is within the group.

BUG=698125
Review-Url: https://codereview.chromium.org/2722983007
Cr-Commit-Position: refs/heads/master@{#454540}
Committed: https://chromium.googlesource.com/chromium/src/+/6b24a72f48297bc66d3e5c67f718f7d6797b4a5c

[caseq, 2017-03-03 03:02:46]

caseq@chromium.org changed reviewers:
+ alph@chromium.org

[alph, 2017-03-03 06:08:53]

The CQ bit was checked by alph@chromium.org

[alph, 2017-03-03 06:08:53]

lgtm

[commit-bot: I haz the power, 2017-03-03 06:09:11]

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, 2017-03-03 07:50:47]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488521333092450, "parent_rev":
"20d1292f80cfedfaa0d521e0fd8c48017a5ac93b", "commit_rev":
"6b24a72f48297bc66d3e5c67f718f7d6797b4a5c"}

[commit-bot: I haz the power, 2017-03-03 07:51:22]

Description was changed from

==========
DevTools Timeline: fix NPE when collapsing the last group

... when selection is within the group.

BUG=698125
==========

to

==========
DevTools Timeline: fix NPE when collapsing the last group

... when selection is within the group.

BUG=698125

Review-Url: https://codereview.chromium.org/2722983007
Cr-Commit-Position: refs/heads/master@{#454540}
Committed:
https://chromium.googlesource.com/chromium/src/+/6b24a72f48297bc66d3e5c67f718...
==========

[commit-bot: I haz the power, 2017-03-03 07:51:23]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/6b24a72f48297bc66d3e5c67f718...