Add support to be able to asynchronously read from a CancelableSyncSocket
on a TYPE_IO message loop thread.  This makes it easy to share a thread
that uses a message loop (e.g. for IPC and other things) and not require
a separate thread to read from the socket.

TEST=Run media_unittests. (--gtest_filter=AsyncSocketIoHandlerTest.*)

Review URL: https://chromiumcodereview.appspot.com/10540047

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@140994 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed