Removed errorneous DCHECK from TaskManager SharedSampler code

Removed errorneous DCHECK from TaskManager SharedSampler code

The DCHECK could be triggered if sampling of results by SharedSampler on
background thread took longer than refresh cycle (1 second) and at the
same time user added or removed one of TaskManager columns handled by
SharedSampler.

This DCHECK was an errorneous assumption. I removed it and added a comment
explaining this situation.

BUG=678471
Review-Url: https://codereview.chromium.org/2612773004
Cr-Commit-Position: refs/heads/master@{#441958}
Committed: https://chromium.googlesource.com/chromium/src/+/929f43478f9acb732ce04c4a1209cf3cd1b7a582

[stanisc, 2017-01-05 23:17:14]

stanisc@chromium.org changed reviewers:
+ afakhry@chromium.org

[stanisc, 2017-01-05 23:17:15]

PTAL!

[stanisc, 2017-01-05 23:17:28]

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

[commit-bot: I haz the power, 2017-01-05 23:17:56]

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, 2017-01-06 00:24:51]

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

[commit-bot: I haz the power, 2017-01-06 00:24:52]

Dry run: This issue passed the CQ dry run.

[afakhry, 2017-01-06 16:49:26]

lgtm

[stanisc, 2017-01-06 17:10:23]

The CQ bit was checked by stanisc@chromium.org

[commit-bot: I haz the power, 2017-01-06 17:10:39]

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, 2017-01-06 17:15:14]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1483722623214540, "parent_rev":
"27c3ece209d8ecddd39fd4331373072e0fba9688", "commit_rev":
"929f43478f9acb732ce04c4a1209cf3cd1b7a582"}

[commit-bot: I haz the power, 2017-01-06 17:15:40]

Description was changed from

==========
Removed errorneous DCHECK from TaskManager SharedSampler code

The DCHECK could be triggered if sampling of results by SharedSampler on
background thread took longer than refresh cycle (1 second) and at the
same time user added or removed one of TaskManager columns handled by
SharedSampler.

This DCHECK was an errorneous assumption. I removed it and added a comment
explaining this situation.

BUG=678471
==========

to

==========
Removed errorneous DCHECK from TaskManager SharedSampler code

The DCHECK could be triggered if sampling of results by SharedSampler on
background thread took longer than refresh cycle (1 second) and at the
same time user added or removed one of TaskManager columns handled by
SharedSampler.

This DCHECK was an errorneous assumption. I removed it and added a comment
explaining this situation.

BUG=678471

Review-Url: https://codereview.chromium.org/2612773004
Cr-Commit-Position: refs/heads/master@{#441958}
Committed:
https://chromium.googlesource.com/chromium/src/+/929f43478f9acb732ce04c4a1209...
==========

[commit-bot: I haz the power, 2017-01-06 17:15:41]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/929f43478f9acb732ce04c4a1209...