Implement posting location tracking in WebThread

Implement posting location tracking in WebThread

This patch adds two variants for postTask and postDelayedTask which
take the original posting location as a parameter. This mirrors the
similar task posting interface of base::TaskRunner and makes it
possible to trace where tasks are being posted from.

BUG=450977
Committed: https://crrev.com/2245d908d8d39bd6f8468ff5546f824fb60bf759
Cr-Commit-Position: refs/heads/master@{#313069}

[Sami, 2015-01-22 20:51:52]

skyostil@chromium.org changed reviewers:
+ sievers@chromium.org

[no sievers, 2015-01-23 20:39:47]

lgtm

https://codereview.chromium.org/869573005/diff/40001/content/child/webthread_...
File content/child/webthread_impl.cc (right):

https://codereview.chromium.org/869573005/diff/40001/content/child/webthread_...
content/child/webthread_impl.cc:114: base::Bind(RunWebThreadTask,
base::Passed(scoped_ptr<Task>(task))),
nit: make_scoped_ptr

[Sami, 2015-01-26 13:41:18]

https://codereview.chromium.org/869573005/diff/40001/content/child/webthread_...
File content/child/webthread_impl.cc (right):

https://codereview.chromium.org/869573005/diff/40001/content/child/webthread_...
content/child/webthread_impl.cc:114: base::Bind(RunWebThreadTask,
base::Passed(scoped_ptr<Task>(task))),
On 2015/01/23 20:39:47, sievers wrote:
> nit: make_scoped_ptr

Thanks, fixed.

[Sami, 2015-01-26 13:41:21]

The CQ bit was checked by skyostil@chromium.org

[commit-bot: I haz the power, 2015-01-26 13:42:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/869573005/60001

[commit-bot: I haz the power, 2015-01-26 15:01:14]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-01-26 15:03:11]

Patchset 4 (id:??) landed as
https://crrev.com/2245d908d8d39bd6f8468ff5546f824fb60bf759
Cr-Commit-Position: refs/heads/master@{#313069}