Network data activity change intent for network interfaces.

The activity notification is received from netd, an intent
DATA_ACTIVITY_CHANGE is then raised for other part of the system to
consume.

Change-Id: Idfcc4763c51c5b314c57f546c12557082f06bebf
diff --git a/services/java/com/android/server/ThrottleService.java b/services/java/com/android/server/ThrottleService.java
index f35a5af..98e6dc0 100644
--- a/services/java/com/android/server/ThrottleService.java
+++ b/services/java/com/android/server/ThrottleService.java
@@ -195,6 +195,7 @@
 
         public void interfaceRemoved(String iface) {}
         public void limitReached(String limitName, String iface) {}
+        public void interfaceClassDataActivityChanged(String label, boolean active) {}
     }