Use a WeakPtr to post a create channel task to the IO thread.

Use a WeakPtr to post a create channel task to the IO thread.

For now, the channel manager is passed as a weak pointer argument and
CHECK fails. This is a temporary debugging aid to help me understand why
ChannelManager has been destroyed at this point. The code will be
changed to handle the case gracefully once I know more.

BUG=542069
Committed: https://crrev.com/b56f54f4f3b37fa178cb38507b652af17ef62a90
Cr-Commit-Position: refs/heads/master@{#353888}

[Anand Mistry (off Chromium), 2015-10-12 02:58:40]

amistry@chromium.org changed reviewers:
+ rockot@chromium.org

[Ken Rockot(use gerrit already), 2015-10-13 16:49:11]

lgtm if you still want to land this

[Anand Mistry (off Chromium), 2015-10-13 21:42:39]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2015-10-13 21:44:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1402453004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1402453004/1

[commit-bot: I haz the power, 2015-10-13 22:57:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-13 22:58:38]

Patchset 1 (id:??) landed as
https://crrev.com/b56f54f4f3b37fa178cb38507b652af17ef62a90
Cr-Commit-Position: refs/heads/master@{#353888}