Revert of Fix posix IPC channel hanging problem.

Revert of Fix posix IPC channel hanging problem. (https://codereview.chromium.org/150893002/)

Reason for revert:
https://crash.corp.google.com/samples?q=reportid=%2702eaaf63ed6fdda9%27
https://crash.corp.google.com/samples?q=reportid=%272ac5bc4dd7c49ced%27

Original issue's description:
> Fix posix IPC channel hanging problem.
> 
> If a channel closes right before a send call, listeners might not be notified of
> the problem, which can cause hangs. This CL fixes that and adds a test that makes
> sure that this does not happen in the future.
> 
> This is cl/30133002 + a memory leak fix.
> 
> BUG=338709
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=250964

TBR=shess@chromium.org,cpu@chromium.org,hubbe@google.com
NOTREECHECKS=true
NOTRY=true
BUG=338709
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251791

[hubbe, 2014-02-18 17:41:45]

Created Revert of Fix posix IPC channel hanging problem.

[commit-bot: I haz the power, 2014-02-18 17:42:08]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/hubbe@chromium.org/170863002/1

[commit-bot: I haz the power, 2014-02-18 17:42:22]

Change committed as 251791

[Fredrik Öhrn, 2014-02-19 08:22:52]

On 2014/02/18 17:41:45, hubbe wrote:
> Created Revert of Fix posix IPC channel hanging problem.

I can't read the links, can you please elaborate why it was reverted?

[hubbe, 2014-02-19 18:51:44]

On 2014/02/19 08:22:52, Fredrik Öhrn wrote:
> On 2014/02/18 17:41:45, hubbe wrote:
> > Created Revert of Fix posix IPC channel hanging problem.
> 
> I can't read the links, can you please elaborate why it was reverted?

Basically, calling OnChannelError() from Send() was a bad idea.
OnChannelErorr() will sometimes tear down the entire environment, so when you
return from Send(), bad things happen.

I have a potentially better fix in https://codereview.chromium.org/172773002,
which delays closing the pipe until it is safe to do so.