Fix Mojo broker crash on Windows.

Fix Mojo broker crash on Windows.

This occurred because a ChildBrokerHost noticed that its connection to the child process died and so it nulled out its channel. On POSIX, this leads to the destruction of the ChildBrokerHost immediately and so the singleton BrokerState is notified synchronously. On Windows, there's another channel for sandboxing related sync IPCs which uses IO completition ports. To ease lifetime issues because of that, the ChildBrokerHost is only deleted in response to errors from that second channel. So if the first channel dies first, it is possible that BrokerState tries to connect to a message pipe in that ChildBrokerState with a null channel.

The fix is to null check the channel and to inform the other side of the message pipe that its peer has died so that it can fire peer closed notifications.

BUG=573244
Committed: https://crrev.com/9b6da52718d7413adb9eec3a2d7f32ce3e04c7ce
Cr-Commit-Position: refs/heads/master@{#367194}

[jam, 2015-12-30 20:24:31]

Patchset #1 (id:1) has been deleted

[jam, 2015-12-30 21:15:19]

jam@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2015-12-30 21:22:38]

LGTM

[jam, 2015-12-30 22:04:46]

The CQ bit was checked by jam@chromium.org

[commit-bot: I haz the power, 2015-12-30 22:05:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1558643002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1558643002/20001

[commit-bot: I haz the power, 2015-12-30 22:10:30]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-12-30 22:11:17]

Description was changed from

==========
Fix Mojo broker crash on Windows.

This occurred because a ChildBrokerHost noticed that its connection to the child
process died and so it nulled out its channel. On POSIX, this leads to the
destruction of the ChildBrokerHost immediately and so the singleton BrokerState
is notified synchronously. On Windows, there's another channel for sandboxing
related sync IPCs which uses IO completition ports. To ease lifetime issues
because of that, the ChildBrokerHost is only deleted in response to errors from
that second channel. So if the first channel dies first, it is possible that
BrokerState tries to connect to a message pipe in that ChildBrokerState with a
null channel.

The fix is to null check the channel and to inform the other side of the message
pipe that its peer has died so that it can fire peer closed notifications.

BUG=573244
==========

to

==========
Fix Mojo broker crash on Windows.

This occurred because a ChildBrokerHost noticed that its connection to the child
process died and so it nulled out its channel. On POSIX, this leads to the
destruction of the ChildBrokerHost immediately and so the singleton BrokerState
is notified synchronously. On Windows, there's another channel for sandboxing
related sync IPCs which uses IO completition ports. To ease lifetime issues
because of that, the ChildBrokerHost is only deleted in response to errors from
that second channel. So if the first channel dies first, it is possible that
BrokerState tries to connect to a message pipe in that ChildBrokerState with a
null channel.

The fix is to null check the channel and to inform the other side of the message
pipe that its peer has died so that it can fire peer closed notifications.

BUG=573244

Committed: https://crrev.com/9b6da52718d7413adb9eec3a2d7f32ce3e04c7ce
Cr-Commit-Position: refs/heads/master@{#367194}
==========

[commit-bot: I haz the power, 2015-12-30 22:11:18]

Patchset 1 (id:??) landed as
https://crrev.com/9b6da52718d7413adb9eec3a2d7f32ce3e04c7ce
Cr-Commit-Position: refs/heads/master@{#367194}