Add Java binding for new getStats implementation.

webrtc/sdk/android/api/org/webrtc/RTCStatsCollectorCallback.java

Index: webrtc/sdk/android/api/org/webrtc/RTCStatsCollectorCallback.java
diff --git a/webrtc/sdk/android/api/org/webrtc/RTCStatsCollectorCallback.java b/webrtc/sdk/android/api/org/webrtc/RTCStatsCollectorCallback.java
new file mode 100644
index 0000000000000000000000000000000000000000..027c1587df6270265b0d546918d1c989568c49d1
--- /dev/null
+++ b/webrtc/sdk/android/api/org/webrtc/RTCStatsCollectorCallback.java
@@ -0,0 +1,17 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/** Interface for receiving stats reports (see webrtc::RTCStatsCollectorCallback). */
+public interface RTCStatsCollectorCallback {
+  /** Called when the stats report is ready. */
+  public void onStatsDelivered(RTCStatsReport report);
+}