Remove second-weak callbacks from V8AbstractEventListener

Remove second-weak callbacks from V8AbstractEventListener

Second-weak callbacks are unsafe with Oilpan because the following scenario can happen:

1) V8 calls the first-weak callback for a wrapper X.
2) V8 drops X from a list scanned by PersistentWrapperVisitor.
3) Oilpan triggers a GC. It traces all wrappers with PersistentWrapperVisitor. X is not traced. X's corresponding DOM object gets collected.
4) V8 calls the second-weak callback for X. It crashes.

BUG=602276
Committed: https://crrev.com/f0cabf25d6d285c0f26a532681ce5070038fd356
Cr-Commit-Position: refs/heads/master@{#386587}

[haraken, 2016-04-12 00:06:53]

haraken@chromium.org changed reviewers:
+ epertoso@chromium.org, jochen@chromium.org

[haraken, 2016-04-12 00:06:53]

PTAL

FYI, I've already removed all other second-weak callbacks for DOM objects -- it
won't affect performance because with oilpan the second-weak callbacks are empty
(it doesn't trigger any destructor).

[haraken, 2016-04-12 00:07:15]

haraken@chromium.org changed reviewers:
+ oilpan-reviews@chromium.org

[jochen (gone - plz use gerrit), 2016-04-12 01:37:40]

lgtm

[haraken, 2016-04-12 01:38:13]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2016-04-12 01:39:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1877153002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1877153002/1

[commit-bot: I haz the power, 2016-04-12 02:59:12]

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

[commit-bot: I haz the power, 2016-04-12 02:59:13]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[haraken, 2016-04-12 03:35:44]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2016-04-12 03:36:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1877153002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1877153002/1

[commit-bot: I haz the power, 2016-04-12 04:37:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-12 04:38:21]

Description was changed from

==========
Remove second-weak callbacks from V8AbstractEventListener

Second-weak callbacks are unsafe with Oilpan because the following scenario can
happen:

1) V8 calls the first-weak callback for a wrapper X.
2) V8 drops X from a list scanned by PersistentWrapperVisitor.
3) Oilpan triggers a GC. It traces all wrappers with PersistentWrapperVisitor. X
is not traced. X's corresponding DOM object gets collected.
4) V8 calls the second-weak callback for X. It crashes.

BUG=602276
==========

to

==========
Remove second-weak callbacks from V8AbstractEventListener

Second-weak callbacks are unsafe with Oilpan because the following scenario can
happen:

1) V8 calls the first-weak callback for a wrapper X.
2) V8 drops X from a list scanned by PersistentWrapperVisitor.
3) Oilpan triggers a GC. It traces all wrappers with PersistentWrapperVisitor. X
is not traced. X's corresponding DOM object gets collected.
4) V8 calls the second-weak callback for X. It crashes.

BUG=602276

Committed: https://crrev.com/f0cabf25d6d285c0f26a532681ce5070038fd356
Cr-Commit-Position: refs/heads/master@{#386587}
==========

[commit-bot: I haz the power, 2016-04-12 04:38:22]

Patchset 1 (id:??) landed as
https://crrev.com/f0cabf25d6d285c0f26a532681ce5070038fd356
Cr-Commit-Position: refs/heads/master@{#386587}