Reorder AudioMessageFilter shutdown. Remove spammy DCHECK.

Reorder AudioMessageFilter shutdown.  Remove spammy DCHECK.

Fixes NULL pointer dereference when the RenderThreadImpl is
destructed but outstanding HTMLMediaElement objects have not
yet been garbage collected.

Reordering will keep audio streams alive slightly longer, but
that should be of no consequence since they would still respond
to graceful shutdown attempts by any living AudioRendererImpls.

BUG=408345
TEST=none

Committed: https://crrev.com/3ba0480e95aac446e3a0f54bdaef9168469f0749
Cr-Commit-Position: refs/heads/master@{#293999}

[DaleCurtis, 2014-09-05 22:51:19]

dalecurtis@chromium.org changed reviewers:
+ scherkus@chromium.org

[scherkus (not reviewing), 2014-09-05 23:04:59]

lgtm w/ nit

https://codereview.chromium.org/517793003/diff/1/content/renderer/media/audio...
File content/renderer/media/audio_renderer_mixer_manager.cc (right):

https://codereview.chromium.org/517793003/diff/1/content/renderer/media/audio...
content/renderer/media/audio_renderer_mixer_manager.cc:24: // ARM owners may be
garbage collected objects.  During process shutdown they
s/ARM/whatever-ARM-stands-for/?

[DaleCurtis, 2014-09-05 23:08:47]

Patchset #2 (id:20001) has been deleted

[DaleCurtis, 2014-09-05 23:09:35]

dalecurtis@chromium.org changed reviewers:
+ jamesr@chromium.org

[DaleCurtis, 2014-09-05 23:09:35]

+jamesr for content/renderer/render_thread_impl.cc

https://codereview.chromium.org/517793003/diff/1/content/renderer/media/audio...
File content/renderer/media/audio_renderer_mixer_manager.cc (right):

https://codereview.chromium.org/517793003/diff/1/content/renderer/media/audio...
content/renderer/media/audio_renderer_mixer_manager.cc:24: // ARM owners may be
garbage collected objects.  During process shutdown they
On 2014/09/05 23:04:59, scherkus wrote:
> s/ARM/whatever-ARM-stands-for/?

Done.

[jamesr, 2014-09-09 00:56:05]

lgtm

[DaleCurtis, 2014-09-09 16:37:57]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-09-09 16:53:36]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/517793003/40001

[commit-bot: I haz the power, 2014-09-09 19:09:00]

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

[commit-bot: I haz the power, 2014-09-09 19:09:01]

Try jobs failed on following builders:
  android_dbg_tests_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tes...)

[DaleCurtis, 2014-09-09 19:15:29]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-09-09 19:16:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/517793003/40001

[commit-bot: I haz the power, 2014-09-09 20:29:03]

Committed patchset #2 (id:40001) as 3fde9654ec2985e902d3db830964c328aa8f7d02

[commit-bot: I haz the power, 2014-09-10 03:55:17]

Patchset 2 (id:??) landed as
https://crrev.com/3ba0480e95aac446e3a0f54bdaef9168469f0749
Cr-Commit-Position: refs/heads/master@{#293999}