Fix build

Change-Id: I81f13f8a573c80f77ff596139fe7589e86d9ee58

Author: samtstern

auth/src/test/java/com/firebase/ui/auth/testhelpers/AutoCompleteTask.java

@@ -59,6 +59,11 @@ public boolean isSuccessful() {
         return mSuccess;
     }
 
+    @Override
+    public boolean isCanceled() {
+        return false;
+    }
+
     @Override
     public TResult getResult() {
         if (mSuccess) {