Add Event and EventTest

remoting/android/javatests/src/org/chromium/chromoting/test/util/MutableReference.java

Index: remoting/android/javatests/src/org/chromium/chromoting/test/util/MutableReference.java
diff --git a/remoting/android/javatests/src/org/chromium/chromoting/test/util/MutableReference.java b/remoting/android/javatests/src/org/chromium/chromoting/test/util/MutableReference.java
new file mode 100644
index 0000000000000000000000000000000000000000..8d21d56348419196d30953a9f3299e6e82b58722
--- /dev/null
+++ b/remoting/android/javatests/src/org/chromium/chromoting/test/util/MutableReference.java
@@ -0,0 +1,35 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chromoting.test.util;
+
+/**
+ * A container of a reference to pass data into or out from a closure. This class is usually useful
+ * in test cases.
+ *
+ * @param <T> The type of reference.
+ */
+public class MutableReference<T> {
+    private T mRef;
+
+    public MutableReference() {
+        clear();
+    }
+
+    public MutableReference(T ref) {
+        set(ref);
+    }
+
+    public void clear() {
+        set(null);
+    }
+
+    public void set(T ref) {
+        mRef = ref;
+    }
+
+    public T get() {
+        return mRef;
+    }
+}