Add in stub backend to be used for jython unit tests.

Change-Id: Idb7a18ce1ddeb8621c688d5580515d10db6edf19
diff --git a/tools/monkeyrunner/src/com/android/monkeyrunner/stub/StubBackend.java b/tools/monkeyrunner/src/com/android/monkeyrunner/stub/StubBackend.java
new file mode 100644
index 0000000..7edff69
--- /dev/null
+++ b/tools/monkeyrunner/src/com/android/monkeyrunner/stub/StubBackend.java
@@ -0,0 +1,26 @@
+package com.android.monkeyrunner.stub;
+
+import com.android.monkeyrunner.MonkeyDevice;
+import com.android.monkeyrunner.MonkeyManager;
+import com.android.monkeyrunner.MonkeyRunnerBackend;
+
+/**
+ * This is a stub backend that doesn't do anything at all.  Useful for
+ * running unit tests.
+ */
+public class StubBackend implements MonkeyRunnerBackend {
+
+    public MonkeyManager createManager(String address, int port) {
+        // We're stub - we've got nothing to do.
+        return null;
+    }
+
+    public MonkeyDevice waitForConnection(long timeout, String deviceId) {
+        // We're stub - we've got nothing to do.
+        return null;
+    }
+
+    public void shutdown() {
+        // We're stub - we've got nothing to do.
+    }
+}