Mojo: Split up Channel::RemoveMessagePipeEndpoint().

Mojo: Split up Channel::RemoveMessagePipeEndpoint().

This really handles two cases. (I want to remove these altogether, but
splitting them up helps my sanity.)

R=brettw@chromium.org

Committed: https://crrev.com/eedce2104a3521228089d3bca17f53f811232b9e
Cr-Commit-Position: refs/heads/master@{#297504}

[viettrungluu, 2014-09-29 21:38:51]

Please review https://codereview.chromium.org/612183002/ first.

[viettrungluu, 2014-09-29 22:35:34]

On 2014/09/29 21:38:51, viettrungluu wrote:
> Please review https://codereview.chromium.org/612183002/ first.

Errrr, don't review this change yet (but do review
https://codereview.chromium.org/612183002/) -- it's probably not right (but
possibly the original code isn't right either).

[viettrungluu, 2014-09-29 23:19:54]

On 2014/09/29 22:35:34, viettrungluu wrote:
> On 2014/09/29 21:38:51, viettrungluu wrote:
> > Please review https://codereview.chromium.org/612183002/ first.
> 
> Errrr, don't review this change yet (but do review
> https://codereview.chromium.org/612183002/) -- it's probably not right (but
> possibly the original code isn't right either).

Okay for review now....

[brettw, 2014-09-30 16:43:02]

lgtm

[viettrungluu, 2014-09-30 19:47:13]

The CQ bit was checked by viettrungluu@chromium.org

[commit-bot: I haz the power, 2014-09-30 19:48:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/612903003/60001

[commit-bot: I haz the power, 2014-09-30 21:32:31]

Committed patchset #4 (id:60001) as 4fa12cbbfde38881f9d1cade969ad59a927dd73d

[commit-bot: I haz the power, 2014-09-30 21:33:08]

Patchset 4 (id:??) landed as
https://crrev.com/eedce2104a3521228089d3bca17f53f811232b9e
Cr-Commit-Position: refs/heads/master@{#297504}