Add base::PostDelayedTask(WithTraits).

Add base::PostDelayedTask(WithTraits).

base::PostDelayedTask(...) is less verbose than
base::CreateTaskRunnerWithTraits(TaskTraits())->PostDelayedTask(...).

The first usage of base::PostDelayedTaskWithTraits will be in
https://codereview.chromium.org/2598483004/.

BUG=553459
Review-Url: https://codereview.chromium.org/2613703003
Cr-Commit-Position: refs/heads/master@{#441723}
Committed: https://chromium.googlesource.com/chromium/src/+/45cc9079ce70043ea3c2a051ba24b69e0ebd2b3a

[fdoray, 2017-01-04 20:41:57]

fdoray@chromium.org changed reviewers:
+ gab@chromium.org, robliao@chromium.org

[fdoray, 2017-01-04 20:41:58]

PTAL

[gab, 2017-01-05 16:43:25]

lgtm

[fdoray, 2017-01-05 17:05:03]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2017-01-05 17:05:26]

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, 2017-01-05 19:24:35]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1483635903469340,
"parent_rev": "229621286f285d38ec7445b123bfe94c88b563f0", "commit_rev":
"45cc9079ce70043ea3c2a051ba24b69e0ebd2b3a"}

[commit-bot: I haz the power, 2017-01-05 19:25:06]

Description was changed from

==========
Add base::PostDelayedTask(WithTraits).

base::PostDelayedTask(...) is less verbose than
base::CreateTaskRunnerWithTraits(TaskTraits())->PostDelayedTask(...).

The first usage of base::PostDelayedTaskWithTraits will be in
https://codereview.chromium.org/2598483004/.

BUG=553459
==========

to

==========
Add base::PostDelayedTask(WithTraits).

base::PostDelayedTask(...) is less verbose than
base::CreateTaskRunnerWithTraits(TaskTraits())->PostDelayedTask(...).

The first usage of base::PostDelayedTaskWithTraits will be in
https://codereview.chromium.org/2598483004/.

BUG=553459

Review-Url: https://codereview.chromium.org/2613703003
Cr-Commit-Position: refs/heads/master@{#441723}
Committed:
https://chromium.googlesource.com/chromium/src/+/45cc9079ce70043ea3c2a051ba24...
==========

[commit-bot: I haz the power, 2017-01-05 19:25:10]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/45cc9079ce70043ea3c2a051ba24...