Revert of Remove stale RFHM check now that unload runs in the background.

Revert of Remove stale RFHM check now that unload runs in the background. (patchset #1 id:1 of https://codereview.chromium.org/617273004/)

Reason for revert:
The new CHECK fails if render_view_host_->is_waiting_for_close_ack_ is true.  See http://crbug.com/420557.

Original issue's description:
> Remove stale RFHM check now that unload runs in the background.
> 
> BUG=402020
> TEST=No behavior change.
> 
> Committed: https://crrev.com/52538dfb0dee9307b87bb688569ec23893a14cab
> Cr-Commit-Position: refs/heads/master@{#297688}

TBR=nasko@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=402020

[Charlie Reis, 2014-10-06 22:39:20]

Created Revert of Remove stale RFHM check now that unload runs in the
background.

[commit-bot: I haz the power, 2014-10-06 22:45:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/632043002/1

[commit-bot: I haz the power, 2014-10-06 22:51:52]

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

[commit-bot: I haz the power, 2014-10-06 22:51:55]

Failed to apply the patch.

[Charlie Reis, 2016-03-03 07:21:31]

Description was changed from

==========
Revert of Remove stale RFHM check now that unload runs in the background.
(patchset #1 id:1 of https://codereview.chromium.org/617273004/)

Reason for revert:
The new CHECK fails if render_view_host_->is_waiting_for_close_ack_ is true. 
See http://crbug.com/420557.

Original issue's description:
> Remove stale RFHM check now that unload runs in the background.
> 
> BUG=402020
> TEST=No behavior change.
> 
> Committed: https://crrev.com/52538dfb0dee9307b87bb688569ec23893a14cab
> Cr-Commit-Position: refs/heads/master@{#297688}

TBR=nasko@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=402020
==========

to

==========
Revert of Remove stale RFHM check now that unload runs in the background.
(patchset #1 id:1 of https://codereview.chromium.org/617273004/)

Reason for revert:
The new CHECK fails if render_view_host_->is_waiting_for_close_ack_ is true. 
See http://crbug.com/420557.

Original issue's description:
> Remove stale RFHM check now that unload runs in the background.
> 
> BUG=402020
> TEST=No behavior change.
> 
> Committed: https://crrev.com/52538dfb0dee9307b87bb688569ec23893a14cab
> Cr-Commit-Position: refs/heads/master@{#297688}

TBR=nasko@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=402020
==========