Rework the per-network URL API.

This addresses API council comments.

Bug: 17112978
Change-Id: I698b243b2b685d1f25414cee72450be3ae0c2bf0
diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index 54d8676..d2a2997 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -128,8 +128,9 @@
     /**
      * Explicitly binds {@code socketfd} to the network designated by {@code netId}.  This
      * overrides any binding via {@link #bindProcessToNetwork}.
+     * @return 0 on success or negative errno on failure.
      */
-    public native static boolean bindSocketToNetwork(int socketfd, int netId);
+    public native static int bindSocketToNetwork(int socketfd, int netId);
 
     /**
      * Protect {@code socketfd} from VPN connections.  After protecting, data sent through