Remove a useless NOTREACHED in nacl_listener.cc

Remove a useless NOTREACHED in nacl_listener.cc

This is a split of https://codereview.chromium.org/315323002/ after patchset #3.

There's more optimization done on a PGO build than on a regular one, this results in some "Unreachable code" warnings that we don't see normally. Currently this warning is disabled for the PGO builds because it triggers on some places like this one.

BUG=380175
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=281828

[Sébastien Marchand, 2014-06-10 21:53:37]

Here's a new CL to discuss about what we should do here, here's some of the
suggestions on https://codereview.chromium.org/315323002/ :
- Just remove this NOTREACHED() (and add a comment about the fact that this
function doesn't return maybe);
- Mark NaClChromeMainStartApp as 'noreturn';
- Don't do anything as this is a special case that triggers only under some
specifics linker optimizations.

[Peter Kasting, 2014-06-10 22:28:20]

So, the summary of my comments from the other thread is that while I'm OK with
this patch as-is, I think it would be even better to add a NORETURN sort of
macro and use it on this function declaration (and any similar calls in the
transitive call chain from here) to make the fact that this doesn't return be
both self-documenting and enforced by the compiler.

[Mark Seaborn, 2014-06-27 23:49:41]

LGTM.  Sorry for being slow.  I wanted to ponder this and read the discussion in
the issue tracker.

NOTREACHED only has an effect in debug builds anyway, so doesn't normally
provide any safety (unlike CHECK), so I'm OK with removing it.

On 2014/06/10 22:28:20, Peter Kasting wrote:
> So, the summary of my comments from the other thread is that while I'm OK with
> this patch as-is, I think it would be even better to add a NORETURN sort of
> macro and use it on this function declaration (and any similar calls in the
> transitive call chain from here) to make the fact that this doesn't return be
> both self-documenting and enforced by the compiler.

Adding a NORETURN sounds reasonable.  For this function, it would be a NaCl-side
change, and the NaCl tree already has a NORETURN macro defined (in
src/include/nacl_compiler_annotations.h).

[Sébastien Marchand, 2014-07-08 14:48:40]

Thanks, committing. I'll add the NORETURN tag in a separate CL (in the nacl
tree)

[Sébastien Marchand, 2014-07-08 14:48:43]

The CQ bit was checked by sebmarchand@chromium.org

[commit-bot: I haz the power, 2014-07-08 14:50:21]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sebmarchand@chromium.org/321273002/1

[commit-bot: I haz the power, 2014-07-08 21:08:25]

Change committed as 281828