Added browser tests to test the BudgetAPI. Also added BudgetAPI to ExperimentalWebPlatformFeatures.

chrome/test/data/budget_service/service_worker.js

Index: chrome/test/data/budget_service/service_worker.js
diff --git a/chrome/test/data/budget_service/service_worker.js b/chrome/test/data/budget_service/service_worker.js
new file mode 100644
index 0000000000000000000000000000000000000000..5ebfb6416e07267edd7132323e872c63baaab7cf
--- /dev/null
+++ b/chrome/test/data/budget_service/service_worker.js
@@ -0,0 +1,52 @@
+// 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.
+
+// Accept messages from the test JavaScript to trigger worker based tests.
+self.addEventListener('message', function (event) {
+  if (event.data.command == 'workerGet') {
+    workerGetBudget();
+  } else if (event.data.command == 'workerReserve') {
+    workerReserve();
+  } else {
+    sendMessageToClients('message', 'error - unknown message request');
+    return;
+  }
+});
+
+// Query for the budget and return the current total.
+function workerGetBudget() {
+  navigator.budget.getBudget().then(function(budget) {
+    sendMessageToClients('message',
+        'ok - budget returned value of ' + budget[0].budgetAt);
+  }, function() {
+    sendMessageToClients('message', 'failed - unable to get budget values');
+  });
+}
+
+// Request a reservation for a silent push.
+function workerReserve() {
+  navigator.budget.reserve('silent-push').then(function(reserved) {
+    if (reserved)
+      sendMessageToClients('message', 'ok - reserved budget');
+    else
+      sendMessageToClients('message', 'failed - not able to reserve budget');
+  }, function() {
+    sendMessageToClients('message',
+        'failed - error while trying to reserve budget');
+  });
+}
+
+function sendMessageToClients(type, data) {
+  const message = JSON.stringify({
+    'type': type,
+    'data': data
+  });
+  clients.matchAll().then(function(clients) {
+    clients.forEach(function(client) {
+      client.postMessage(message);
+    });
+  }, function(error) {
+    console.log(error);
+  });
+}