Limit stack-allocated uses of CancellableTaskFactory(PassOwnPtr<Closure>).

Limit stack-allocated uses of CancellableTaskFactory(PassOwnPtr<Closure>).

Classes that keep a CancellableTaskFactory should create() these via the
provided factory method, which takes care of creating the task factory's
closure in a manner that doesn't cause an (Oilpan) leak.

Not using the factory method is convenient when testing, so accommodate
this by way of a protected CancellableTaskFactory<> constructor, and use
it in unit tests. The unit tests exercise functionality rather than direct
usage by Blink objects, so hiding the constructor is considered acceptable.

R=haraken
BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201916

[sof, 2015-09-08 13:05:04]

sigbjornf@opera.com changed reviewers:
+ haraken@chromium.org, scheduler-bugs@chromium.org

[sof, 2015-09-08 13:05:04]

please take a look/consider.

I'd like to steer users away from using the CancellableTaskFactory ctor
directly. This is one way to do that - wdyt?

[haraken, 2015-09-08 14:08:29]

LGTM

[sof, 2015-09-08 14:29:12]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-09-08 14:29:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1320023009/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1320023009/1

[commit-bot: I haz the power, 2015-09-08 15:09:50]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201916