[mojo-edk] Fix bootstrap NodeChannel Start/ShutDown race

[mojo-edk] Fix bootstrap NodeChannel Start/ShutDown race

If the parent bootstrap signals an error very early in
NodeController startup, it can be ShutDown() before
Start() is invoked on the IO thread via
ConnectoToParentOnIOThread.

This changes Start() to gracefully handle a null
|channel_|.

BUG=610337
R=amistry@chromium.org

Review-Url: https://codereview.chromium.org/1985993002
Cr-Commit-Position: refs/heads/master@{#394055}
(cherry picked from commit 1febcb4dfce7928a6d4bee93888bdb88bfa18ce4)

Committed: https://chromium.googlesource.com/chromium/src/+/9075528e0b9897b4775e764cacfff08b0eb79979

[Ken Rockot(use gerrit already), 2016-05-18 21:56:03]

Description was changed from

==========
[mojo-edk] Fix bootstrap NodeChannel Start/ShutDown race

If the parent bootstrap signals an error very early in
NodeController startup, it can be ShutDown() before
Start() is invoked on the IO thread via
ConnectoToParentOnIOThread.

This changes Start() to gracefully handle a null
|channel_|.

BUG=610337
R=amistry@chromium.org

Review-Url: https://codereview.chromium.org/1985993002
Cr-Commit-Position: refs/heads/master@{#394055}
(cherry picked from commit 1febcb4dfce7928a6d4bee93888bdb88bfa18ce4)
==========

to

==========
[mojo-edk] Fix bootstrap NodeChannel Start/ShutDown race

If the parent bootstrap signals an error very early in
NodeController startup, it can be ShutDown() before
Start() is invoked on the IO thread via
ConnectoToParentOnIOThread.

This changes Start() to gracefully handle a null
|channel_|.

BUG=610337
R=amistry@chromium.org

Review-Url: https://codereview.chromium.org/1985993002
Cr-Commit-Position: refs/heads/master@{#394055}
(cherry picked from commit 1febcb4dfce7928a6d4bee93888bdb88bfa18ce4)

Committed:
https://chromium.googlesource.com/chromium/src/+/9075528e0b9897b4775e764cacff...
==========

[Ken Rockot(use gerrit already), 2016-05-18 21:56:04]

Committed patchset #1 (id:1) manually as
9075528e0b9897b4775e764cacfff08b0eb79979.