Defer failure in CallbackGroup until all are completed

This avoids staged CallbackGroups like used in CS2 or SBS2
from triggering multiple error panels when an earlier group
fails and is unable to "finish" a later group.

Change-Id: I05a976fa8fa635a2035ed0ceeb69dfbd2a451b54

gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/CallbackGroup.java

@@ -108,6 +108,15 @@ public class CallbackGroup {
     }
   }
 
+  private void applyAllFailed() {
+    if (failed && finalAdded && remaining.isEmpty()) {
+      for (CallbackImpl<?> cb : callbacks) {
+        cb.applyFailed();
+      }
+      callbacks.clear();
+    }
+  }
+
   private <T> Callback<T> handleAdd(AsyncCallback<T> cb) {
     if (failed) {
       cb.onFailure(failedThrowable);
@@ -140,10 +149,6 @@ public class CallbackGroup {
 
     @Override
     public void onSuccess(T value) {
-      if (failed) {
-        return;
-      }
-
       this.result = value;
       remaining.remove(this);
       CallbackGroup.this.applyAllSuccess();
@@ -151,19 +156,12 @@ public class CallbackGroup {
 
     @Override
     public void onFailure(Throwable caught) {
-      if (failed) {
-        return;
+      if (!failed) {
+        failed = true;
+        failedThrowable = caught;
       }
-
-      failed = true;
-      failedThrowable = caught;
-      for (CallbackImpl<?> cb : callbacks) {
-        cb.delegate.onFailure(failedThrowable);
-        cb.delegate = null;
-        cb.result = null;
-      }
-      callbacks.clear();
-      remaining.clear();
+      remaining.remove(this);
+      CallbackGroup.this.applyAllFailed();
     }
 
     void applySuccess() {
@@ -174,5 +172,14 @@ public class CallbackGroup {
         result = null;
       }
     }
+
+    void applyFailed() {
+      AsyncCallback<T> cb = delegate;
+      if (cb != null) {
+        delegate = null;
+        result = null;
+        cb.onFailure(failedThrowable);
+      }
+    }
   }
 }