NaCl: Allow setting up multiple sockets for subprocess instead of just one

Remove the "channel number" parameter from messages, since this is now
fixed in the NaCl plugin code in sel_main_chrome.c.

Replace pair_ and descriptor_ with sockets_for_renderer_ and
sockets_for_sel_ldr_.

NaClProcessMsg_Start: Pass an array of FDs instead of one FD.

ViewHostMsg_LaunchNaCl:
 * Add socket count.
 * Return an array of FDs instead of one FD.

Expose this functionality to the NaCl plugin via a new function,
"launch_nacl_process_multi_fd".

BUG=50626
TEST=nacl_ui_tests

Review URL: http://codereview.chromium.org/2832093

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@54113 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed