Add toString in NetworkFactory.

Needed some additional logging to track down this bug
so add toString to capture the state.

bug:18569575
Change-Id: I4047b8f8797bac09bcff31e99d9cb117abb04df4
diff --git a/core/java/android/net/NetworkFactory.java b/core/java/android/net/NetworkFactory.java
index 6ddd8b3..9b80e74 100644
--- a/core/java/android/net/NetworkFactory.java
+++ b/core/java/android/net/NetworkFactory.java
@@ -274,4 +274,12 @@
     protected void log(String s) {
         Log.d(LOG_TAG, s);
     }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder("{").append(LOG_TAG).append(" - ScoreFilter=").
+                append(mScore).append(", Filter=").append(mCapabilityFilter).append(", requests=").
+                append(mNetworkRequests.size()).append("}");
+        return sb.toString();
+    }
 }