Add ConnectivityManager.unregisterNetworkCallback(PendingIntent) API

This better pairs up with
registerNetworkCallback(NetworkRequest, PendingIntent).

Bug:22175708
Change-Id: I336df3f48a0b814f1cbeba6d00afc4e6cc536483

core/java/android/net/ConnectivityManager.java

@@ -2565,7 +2565,7 @@ public class ConnectivityManager {
      * replaced by this one, effectively releasing the previous {@link NetworkRequest}.
      * <p>
      * The request may be released normally by calling
-     * {@link #releaseNetworkRequest(android.app.PendingIntent)}.
+     * {@link #unregisterNetworkCallback(android.app.PendingIntent)}.
      * <p>This method requires the caller to hold the permission
      * {@link android.Manifest.permission#ACCESS_NETWORK_STATE}.
      * @param request {@link NetworkRequest} describing this request.
@@ -2618,6 +2618,19 @@ public class ConnectivityManager {
         } catch (RemoteException e) {}
     }
 
+    /**
+     * Unregisters a callback previously registered via
+     * {@link #registerNetworkCallback(NetworkRequest, android.app.PendingIntent)}.
+     *
+     * @param operation A PendingIntent equal (as defined by {@link Intent#filterEquals}) to the
+     *                  PendingIntent passed to
+     *                  {@link #registerNetworkCallback(NetworkRequest, android.app.PendingIntent)}.
+     *                  Cannot be null.
+     */
+    public void unregisterNetworkCallback(PendingIntent operation) {
+        releaseNetworkRequest(operation);
+    }
+
     /**
      * Informs the system whether it should switch to {@code network} regardless of whether it is
      * validated or not. If {@code accept} is true, and the network was explicitly selected by the