Revert r251271 "Setuid sandbox: exit(2) on SIGABRT" Make Linux build again.

TBR=jln

Review URL: https://codereview.chromium.org/166303002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251273 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251273