Add the new version for the POSIX-specific version of LaunchProcess.

Add the new version for the POSIX-specific version of LaunchProcess.

The old version will be removed once all consumers are updated.

BUG=417532
Committed: https://crrev.com/02a9986ca1c0485ca8837e976c7f36e21437109b
Cr-Commit-Position: refs/heads/master@{#310924}

[rvargas (doing something else), 2015-01-09 22:51:53]

rvargas@chromium.org changed reviewers:
+ thestig@chromium.org

[Lei Zhang, 2015-01-09 23:01:45]

lgtm

[rvargas (doing something else), 2015-01-09 23:39:07]

The CQ bit was checked by rvargas@chromium.org

[commit-bot: I haz the power, 2015-01-09 23:41:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/827493004/1

[commit-bot: I haz the power, 2015-01-10 00:46:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-10 00:47:42]

Patchset 1 (id:??) landed as
https://crrev.com/02a9986ca1c0485ca8837e976c7f36e21437109b
Cr-Commit-Position: refs/heads/master@{#310924}