Add stats collector

java/org/rocksdb/test/StatsCallbackMock.java

@@ -0,0 +1,22 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb.test;
+
+import org.rocksdb.*;
+
+public class StatsCallbackMock implements StatisticsCollectorCallback {
+  public int tickerCallbackCount = 0;
+  public int histCallbackCount = 0;
+        
+  public void tickerCallback(TickerType tickerType, long tickerCount) {
+    tickerCallbackCount++;
+  }
+    
+  public void histogramCallback(HistogramType histType,
+      HistogramData histData) {
+    histCallbackCount++;
+  }
+}