Document registration of Oilpan weak callbacks.

Document registration of Oilpan weak callbacks.

R=
BUG=

Committed: https://crrev.com/b5a020778f3f384ceafb726556596803747845e4
Cr-Commit-Position: refs/heads/master@{#390860}

[sof, 2016-04-30 11:12:35]

sigbjornf@opera.com changed reviewers:
+ oilpan-reviews@chromium.org

[sof, 2016-04-30 11:12:35]

please take a look.

[haraken, 2016-04-30 17:51:58]

LGTM

It would be worth mentioning that weak callbacks are not called if the pointing
object dies at the same time -- if you expect the callback getting called
unconditionally, you need to use a pre-finalizer.

[sof, 2016-04-30 18:18:47]

On 2016/04/30 17:51:58, haraken wrote:
> LGTM
> 
> It would be worth mentioning that weak callbacks are not called if the
pointing
> object dies at the same time -- if you expect the callback getting called
> unconditionally, you need to use a pre-finalizer.

Added a paragraph covering that - if the object with the weak reference's
trace() method isn't called, you shouldn't expect weak processing to occur for
it. I don't think we have a current example of that in Blink.

Usual finalization mechanism are needed for that; prefinalizer or the more
natural destructor, eager or not.

[sof, 2016-04-30 19:10:28]

The CQ bit was checked by sigbjornf@opera.com

[sof, 2016-04-30 19:10:29]

The patchset sent to the CQ was uploaded after l-g-t-m from haraken@chromium.org
Link to the patchset: https://codereview.chromium.org/1935943002/#ps20001
(title: "Mention weak callbacks vs finalization")

[commit-bot: I haz the power, 2016-04-30 19:10:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1935943002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1935943002/20001

[commit-bot: I haz the power, 2016-04-30 20:16:44]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-30 20:18:08]

Description was changed from

==========
Document registration of Oilpan weak callbacks.

R=
BUG=
==========

to

==========
Document registration of Oilpan weak callbacks.

R=
BUG=

Committed: https://crrev.com/b5a020778f3f384ceafb726556596803747845e4
Cr-Commit-Position: refs/heads/master@{#390860}
==========

[commit-bot: I haz the power, 2016-04-30 20:18:09]

Patchset 2 (id:??) landed as
https://crrev.com/b5a020778f3f384ceafb726556596803747845e4
Cr-Commit-Position: refs/heads/master@{#390860}