Make BaseNetworkObserver available to core code

Currently BaseNetworkObserver is in frameworks/base/services, but
there is code in frameworks/base/core that could use it. This
code typically extends INetworkManagementEventObserver.stub
because BaseNetworkObserver is not available.

Move BaseNetworkObserver to frameworks/base/core without changing
its package name, and use it to simplify two callers. The third
caller, Tethering, is much larger, and I'm not sure it's
appropriate to change it.

Bug: 10232006
Change-Id: Ifc0f2e619e3424e27e35730c048a1cc523df345e

services/java/com/android/server/CommonTimeManagementService.java

@@ -40,6 +40,8 @@ import android.os.ServiceManager;
 import android.os.SystemProperties;
 import android.util.Log;
 
+import com.android.server.net.BaseNetworkObserver;
+
 /**
  * @hide
  * <p>CommonTimeManagementService manages the configuration of the native Common Time service,
@@ -104,9 +106,7 @@ class CommonTimeManagementService extends Binder {
     /*
      * Callback handler implementations.
      */
-    private INetworkManagementEventObserver mIfaceObserver =
-        new INetworkManagementEventObserver.Stub() {
-
+    private INetworkManagementEventObserver mIfaceObserver = new BaseNetworkObserver() {
         public void interfaceStatusChanged(String iface, boolean up) {
             reevaluateServiceState();
         }
@@ -119,9 +119,6 @@ class CommonTimeManagementService extends Binder {
         public void interfaceRemoved(String iface) {
             reevaluateServiceState();
         }
-        public void limitReached(String limitName, String iface) { }
-
-        public void interfaceClassDataActivityChanged(String label, boolean active) {}
     };
 
     private BroadcastReceiver mConnectivityMangerObserver = new BroadcastReceiver() {