Make GetSockDiag really return an InetDiagMsg, not a tuple.

Change-Id: I10fbb3bcecfc61082a5cc67419bf3c6616615398

tests/net_test/sock_diag.py

@@ -226,7 +226,7 @@ class SockDiag(netlink.NetlinkSocket):
   def GetSockDiag(self, req):
     """Gets an InetDiagMsg from the kernel for the specified request."""
     self._SendNlRequest(SOCK_DIAG_BY_FAMILY, req.Pack(), netlink.NLM_F_REQUEST)
-    return self._GetMsg(InetDiagMsg)
+    return self._GetMsg(InetDiagMsg)[0]
 
   @staticmethod
   def DiagReqFromDiagMsg(d, protocol):

tests/net_test/sock_diag_test.py

@@ -128,7 +128,7 @@ class SockDiagTest(multinetwork_base.MultiNetworkBaseTest):
         req = self.sock_diag.DiagReqFromSocket(sock)
         req.id.cookie = cookie
         req.states = 1 << diag_msg.state
-        diag_msg, attrs = self.sock_diag.GetSockDiag(req)
+        diag_msg = self.sock_diag.GetSockDiag(req)
         self.assertSockDiagMatchesSocket(sock, diag_msg)