On Linux, move the passing of filedescriptors to a dedicated socketpair().

On Linux, move the passing of filedescriptors to a dedicated socketpair().

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

[agl, 2009-09-01 20:27:06]

Need to remove the .d files. LGTM.

http://codereview.chromium.org/177049/diff/2001/91
File ipc/ipc_channel_posix.cc (right):

http://codereview.chromium.org/177049/diff/2001/91#newcode359
Line 359: // As we cannot anticipate, when the sender will provide us with file
remove the comma

http://codereview.chromium.org/177049/diff/2001/91#newcode573
Line 573: DCHECK(payload_len % sizeof(int) == 0);
DCHECK_EQ

http://codereview.chromium.org/177049/diff/2001/91#newcode695
Line 695: if (output_queue_.empty()) {
Don't change the style of existing code unless it's outside the style guide.

http://codereview.chromium.org/177049/diff/2001/91#newcode699
Line 699: if (pipe_ == -1) {
same here.