Add an Android sample app for Telemetry tests.

tools/perf/perf_helper_app/src/org/chromium/perf_helper/PushAppsToBackgroundActivity.java

Index: tools/perf/perf_helper_app/src/org/chromium/perf_helper/PushAppsToBackgroundActivity.java
diff --git a/tools/perf/perf_helper_app/src/org/chromium/perf_helper/PushAppsToBackgroundActivity.java b/tools/perf/perf_helper_app/src/org/chromium/perf_helper/PushAppsToBackgroundActivity.java
new file mode 100644
index 0000000000000000000000000000000000000000..538dbc9527729b3dec6bdc3e5b774506788cd727
--- /dev/null
+++ b/tools/perf/perf_helper_app/src/org/chromium/perf_helper/PushAppsToBackgroundActivity.java
@@ -0,0 +1,21 @@
+// 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.perf_helper;
+
+import android.app.Activity;
+import android.os.Bundle;
+
+/**
+ * This activity is used in performance test to push other apps
+ * to the background while running automated user stories.
+ */
+public class PushAppsToBackgroundActivity extends Activity {
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_push_apps_to_background);
+    }
+}