Reland r290125: Close all active PeerConnections upon OS suspend

Reland r290125: Close all active PeerConnections upon OS suspend

This replaces the CHECK with an if statement because the RenderProcessHost
is cleaned up before deletion, which means it can be unregistered from the
list of available RenderProcessHosts before being destructed (hence CHECK
firing).

BUG=403618, 404715
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=290757

[vrk (LEFT CHROMIUM), 2014-08-19 01:01:10]

Had to revert r290125 because the CHECK was firing. This is the CL to reland it.

Please take a look at the CL description and the diff - this is a 2-line change.

[nasko, 2014-08-19 17:17:41]

It is unfortunate that we unregister the process and delete it later, leaving
the filters in place. LGTM on your change.

[jiayl, 2014-08-19 17:41:45]

lgtm

[jiayl, 2014-08-19 17:41:46]

lgtm

[vrk (LEFT CHROMIUM), 2014-08-19 17:45:45]

The CQ bit was checked by vrk@chromium.org

[commit-bot: I haz the power, 2014-08-19 17:46:55]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vrk@chromium.org/482333003/40001

[commit-bot: I haz the power, 2014-08-19 19:06:28]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_clang_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_clang_d...)

[vrk (LEFT CHROMIUM), 2014-08-19 19:35:01]

The CQ bit was unchecked by vrk@chromium.org

[vrk (LEFT CHROMIUM), 2014-08-20 01:19:58]

The CQ bit was checked by vrk@chromium.org

[commit-bot: I haz the power, 2014-08-20 01:20:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vrk@chromium.org/482333003/60001

[commit-bot: I haz the power, 2014-08-20 03:08:52]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  win_chromium_x64_rel_swarming on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-20 04:10:24]

Committed patchset #3 (60001) as 290757