(Patch by Markus)
This allows the fast path to use read()/write() instead of recvmsg()/sendmsg()
which is much cheaper for the Seccomp sandbox.
Also, fixed minor seccomp sandbox issues discovered by this change.
BUG=19120
ISSUE=164373
http://codereview.chromium.org/177049
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25518 0039d316-1c4b-4281-b951-d872f2087c98