Remove WTF::isShutdown()

Remove WTF::isShutdown()

Now it's unused.

BUG=639244
Committed: https://crrev.com/47f9c2d1ca781e1e4df5dc05b74200a6ba696afe
Cr-Commit-Position: refs/heads/master@{#414030}

[haraken, 2016-08-24 05:41:55]

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

[commit-bot: I haz the power, 2016-08-24 05:42:15]

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

[haraken, 2016-08-24 05:42:19]

haraken@chromium.org changed reviewers:
+ yutak@chromium.org

[haraken, 2016-08-24 05:42:20]

PTAL

[Yuta Kitamura, 2016-08-24 08:18:34]

lgtm

[commit-bot: I haz the power, 2016-08-24 09:24:03]

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

[commit-bot: I haz the power, 2016-08-24 09:24:04]

Dry run: This issue passed the CQ dry run.

[haraken, 2016-08-24 09:26:41]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2016-08-24 09:27:15]

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, 2016-08-24 09:32:58]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-24 09:34:50]

Description was changed from

==========
Remove WTF::isShutdown()

Now it's unused.

BUG=639244
==========

to

==========
Remove WTF::isShutdown()

Now it's unused.

BUG=639244

Committed: https://crrev.com/47f9c2d1ca781e1e4df5dc05b74200a6ba696afe
Cr-Commit-Position: refs/heads/master@{#414030}
==========

[commit-bot: I haz the power, 2016-08-24 09:34:51]

Patchset 1 (id:??) landed as
https://crrev.com/47f9c2d1ca781e1e4df5dc05b74200a6ba696afe
Cr-Commit-Position: refs/heads/master@{#414030}

[haraken, 2016-09-05 00:30:11]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2311713002/ by haraken@chromium.org.

The reason for reverting is: I'll revert r413430 and its dependent CLs because
r413430 caused issue 642072.

The problem is that we cannot simply remove blink::shutdown because the
following scenario can happen:

1) blink::shutdown is not called. Workers are still running.
2) RenderThreadImpl gets destructed. MessageLoop gets destructed.
3) The workers may access the RenderThreadImpl and MessageLoop.

To fix the problem, we need to call ProcessDied() and forcibly kill the renderer
process at the end of RenderThreadImpl::Shutdown().
.