Destroy observers eagerly when StopTracking is called.

Destroy observers eagerly when StopTracking is called.

Currently, if we decide to StopTracking a navigation at commit time,
some callbacks may still get invoked. In particular, browser-initiated
callbacks like WasShown and WasHidden may be called; timing and other
callbacks should be prevented by RenderPageTrackDecider policy in the
render process. This change makes us destroy observers eagerly at the
time StopTracking() gets called, which prevents us from invoking any
subsequent callbacks on observers after this point.

BUG=648361
Committed: https://crrev.com/16e566dd1cd74c5a5def9a1d60077f6973e9f000
Cr-Commit-Position: refs/heads/master@{#419729}

[Bryan McQuade, 2016-09-19 19:49:40]

The CQ bit was checked by bmcquade@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-19 19:50:29]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Bryan McQuade, 2016-09-19 20:40:42]

Description was changed from

==========
Destroy observers eagerly when StopTracking is called.

BUG=648361
==========

to

==========
Destroy observers eagerly when StopTracking is called.

Currently, if we decide to StopTracking a navigation at commit time,
some callbacks may still get invoked. In particular, browser-initiated
callbacks like WasShown and WasHidden may be called; timing and other
callbacks should be prevented by RenderPageTrackDecider policy in the
render process. This change makes us destroy observers eagerly at the
time StopTracking() gets called, which prevents us from invoking any
subsequent callbacks on observers after this point.

BUG=648361
==========

[Bryan McQuade, 2016-09-19 20:40:42]

bmcquade@chromium.org changed reviewers:
+ csharrison@chromium.org

[Bryan McQuade, 2016-09-19 20:41:48]

PTAL

[commit-bot: I haz the power, 2016-09-19 20:44:34]

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

[commit-bot: I haz the power, 2016-09-19 20:44:36]

Dry run: This issue passed the CQ dry run.

[Charlie Harrison, 2016-09-19 20:55:32]

LGTM

[Bryan McQuade, 2016-09-20 12:28:47]

The CQ bit was checked by bmcquade@chromium.org

[commit-bot: I haz the power, 2016-09-20 12:29:03]

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, 2016-09-20 12:33:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-20 12:35:10]

Description was changed from

==========
Destroy observers eagerly when StopTracking is called.

Currently, if we decide to StopTracking a navigation at commit time,
some callbacks may still get invoked. In particular, browser-initiated
callbacks like WasShown and WasHidden may be called; timing and other
callbacks should be prevented by RenderPageTrackDecider policy in the
render process. This change makes us destroy observers eagerly at the
time StopTracking() gets called, which prevents us from invoking any
subsequent callbacks on observers after this point.

BUG=648361
==========

to

==========
Destroy observers eagerly when StopTracking is called.

Currently, if we decide to StopTracking a navigation at commit time,
some callbacks may still get invoked. In particular, browser-initiated
callbacks like WasShown and WasHidden may be called; timing and other
callbacks should be prevented by RenderPageTrackDecider policy in the
render process. This change makes us destroy observers eagerly at the
time StopTracking() gets called, which prevents us from invoking any
subsequent callbacks on observers after this point.

BUG=648361

Committed: https://crrev.com/16e566dd1cd74c5a5def9a1d60077f6973e9f000
Cr-Commit-Position: refs/heads/master@{#419729}
==========

[commit-bot: I haz the power, 2016-09-20 12:35:11]

Patchset 1 (id:??) landed as
https://crrev.com/16e566dd1cd74c5a5def9a1d60077f6973e9f000
Cr-Commit-Position: refs/heads/master@{#419729}