IPC: Fix attachment brokering race condition.

IPC: Fix attachment brokering race condition.

A channel must be registered as a broker communication channel before it is
connected. When possible, invert the sequence of the call to connect a channel,
and the call to register the channel as a broker. In some cases, the channel
constructor and the channel initializer had to be separated, so that the
registration could happen in between.

This requirement is now enforced by a CHECK, which verifies that a channel
cannot be registered after it is connected.

BUG=598088
Review URL: https://codereview.chromium.org/1903663004

Cr-Commit-Position: refs/heads/master@{#389618}
(cherry picked from commit 9097190cafdecfb1b5796b65c83af92e861ccaf8)

Committed: https://chromium.googlesource.com/chromium/src/+/a132709b08846c8ac75bead8d97a0fec2cb30ace

[erikchen, 2016-04-26 23:31:08]

Description was changed from

==========
IPC: Fix attachment brokering race condition.

A channel must be registered as a broker communication channel before it is
connected. When possible, invert the sequence of the call to connect a channel,
and the call to register the channel as a broker. In some cases, the channel
constructor and the channel initializer had to be separated, so that the
registration could happen in between.

This requirement is now enforced by a CHECK, which verifies that a channel
cannot be registered after it is connected.

BUG=598088

Review URL: https://codereview.chromium.org/1903663004

Cr-Commit-Position: refs/heads/master@{#389618}
(cherry picked from commit 9097190cafdecfb1b5796b65c83af92e861ccaf8)
==========

to

==========
IPC: Fix attachment brokering race condition.

A channel must be registered as a broker communication channel before it is
connected. When possible, invert the sequence of the call to connect a channel,
and the call to register the channel as a broker. In some cases, the channel
constructor and the channel initializer had to be separated, so that the
registration could happen in between.

This requirement is now enforced by a CHECK, which verifies that a channel
cannot be registered after it is connected.

BUG=598088

Review URL: https://codereview.chromium.org/1903663004

Cr-Commit-Position: refs/heads/master@{#389618}
(cherry picked from commit 9097190cafdecfb1b5796b65c83af92e861ccaf8)

Committed:
https://chromium.googlesource.com/chromium/src/+/a132709b08846c8ac75bead8d97a...
==========

[erikchen, 2016-04-26 23:31:10]

Committed patchset #1 (id:1) manually as
a132709b08846c8ac75bead8d97a0fec2cb30ace.