Push API: test that default notification is shown on Android when needed.

chrome/test/data/push_messaging/push_messaging_test_worker_android.js

 // Copyright 2015 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.
 
+// The MessagePort to communicate with the client.
 var messagePort = null;
 
-onmessage = event => {
-  messagePort = event.data;
-  messagePort.postMessage('ready');
+// If true this service worker will show a notification when a push message is
+// received.
+var notifyOnPush = true;
+
+// The number of notifications shown.
+var notificationCounter = 0;
+
+// Sends a message to the test, via the page.
+function sendToTest(message) {
+  messagePort.postMessage(JSON.stringify({
+    'type': 'sendToTest',
+    'data': message
+  }));
+}
+
+self.onmessage = event => {
+  if (event.data instanceof MessagePort) {
+    messagePort = event.data;
+    messagePort.postMessage('ready');
+    return;
+  }
+
+  var message = JSON.parse(event.data);
+  if (message.type == 'setNotifyOnPush') {
+    notifyOnPush = message.data;
+    sendToTest('setNotifyOnPush ' + message.data + ' ok');
+    return;
+  }
+
+  sendToTest('Unknown message type.');
 };
 
-onpush = event =>
-  event.waitUntil(registration.showNotification('push notification'));
+self.onpush = event => {
+  if (notifyOnPush) {
+    notificationCounter++;
+    event.waitUntil(registration.showNotification(
+        'push notification ' + notificationCounter));
+  }
+};