Add an optional channel name to the extension message connect event.

Also changed the way port IDs work internally to reduce confusion.  Each end of the port has its own ID, not the ID of its opposite end.

BUG=13706
TEST=no

Review URL: http://codereview.chromium.org/155381

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20519 0039d316-1c4b-4281-b951-d872f2087c98
12 files changed