Switch to gwtjsonrpc's new Handler based status update API

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/src/main/java/com/google/gerrit/client/Gerrit.java b/src/main/java/com/google/gerrit/client/Gerrit.java
index 25e5aeb..3ae578a 100644
--- a/src/main/java/com/google/gerrit/client/Gerrit.java
+++ b/src/main/java/com/google/gerrit/client/Gerrit.java
@@ -198,7 +198,10 @@
     };
     RootPanel.get("gerrit_body").add(body);
 
-    JsonUtil.addRpcStatusListener(new RpcStatus(menuArea));
+    final RpcStatus rpcStatus = new RpcStatus(menuArea);
+    JsonUtil.addRpcStartHandler(rpcStatus);
+    JsonUtil.addRpcCompleteHandler(rpcStatus);
+
     SYSTEM_SVC.loadGerritConfig(new GerritCallback<GerritConfig>() {
       public void onSuccess(final GerritConfig result) {
         Common.setGerritConfig(result);
diff --git a/src/main/java/com/google/gerrit/client/RpcStatus.java b/src/main/java/com/google/gerrit/client/RpcStatus.java
index 56e4a20..783e84b 100644
--- a/src/main/java/com/google/gerrit/client/RpcStatus.java
+++ b/src/main/java/com/google/gerrit/client/RpcStatus.java
@@ -18,9 +18,12 @@
 import com.google.gwt.user.client.ui.InlineLabel;
 import com.google.gwt.user.client.ui.Label;
 import com.google.gwt.user.client.ui.Panel;
-import com.google.gwtjsonrpc.client.RpcStatusListener;
+import com.google.gwtjsonrpc.client.RpcCompleteEvent;
+import com.google.gwtjsonrpc.client.RpcCompleteHandler;
+import com.google.gwtjsonrpc.client.RpcStartEvent;
+import com.google.gwtjsonrpc.client.RpcStartHandler;
 
-public class RpcStatus implements RpcStatusListener {
+public class RpcStatus implements RpcStartHandler, RpcCompleteHandler {
   private static int hideDepth;
 
   /** Execute code, hiding the RPCs they execute from being shown visually. */
@@ -49,7 +52,8 @@
     r.add(loading);
   }
 
-  public void onCallStart() {
+  @Override
+  public void onRpcStart(final RpcStartEvent event) {
     if (++activeCalls == 1) {
       if (hideDepth == 0) {
         loading.setVisible(true);
@@ -57,7 +61,8 @@
     }
   }
 
-  public void onCallEnd() {
+  @Override
+  public void onRpcComplete(final RpcCompleteEvent event) {
     if (--activeCalls == 0) {
       loading.setVisible(false);
     }