Add a new GetTlsUniqueChannelBinding method to SSLSocket, and implement nss version.

net/socket/socket_test_util.cc

Index: net/socket/socket_test_util.cc
diff --git a/net/socket/socket_test_util.cc b/net/socket/socket_test_util.cc
index ff66830230ad73c2efb139795a2f191a7812f667..8bc5183bf0458d00cd4daf2fd2d5c9a50fa87b0a 100644
--- a/net/socket/socket_test_util.cc
+++ b/net/socket/socket_test_util.cc
@@ -717,6 +717,14 @@ int MockClientSocket::ExportKeyingMaterial(const base::StringPiece& label,
   return OK;
 }
 
+int MockClientSocket::GetTlsUniqueChannelBinding(unsigned char* out,
+                                                 unsigned int *outlen,
+                                                 unsigned int outlen_max) {
+  memset(out, 'B', outlen_max);
+  *outlen = outlen_max;

[wtc, 2012/07/30 20:05:08]

I wonder if we should memset 12 bytes and store 12 in *outlen?

If we do so, we need to make sure outlen_max >= 12.
(We don't seem to have an error code for "buffer too small".
I guess we can use ERR_INVALID_ARGUMENT as a substitute.)

[Ryan Hamilton, 2012/07/30 21:37:58]

Done.

+  return OK;
+}
+
 ServerBoundCertService* MockClientSocket::GetServerBoundCertService() const {
   NOTREACHED();
   return NULL;