Begin to enable extension APIs in Extension Service Worker.

chrome/test/data/extensions/api_test/service_worker/tabs_create/sw.js

+// 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.
+
+self.onmessage = function(e) {
+  if (e.data == 'createTab') {
+    try {
+      chrome.tabs.create({'url': 'http://www.google.com'}, function(tabs) {
+        e.ports[0].postMessage('chrome.tabs.create callback');
+      });
+    } catch (e) {
+      e.ports[0].postMessage('FAILURE');
+    }
+  } else {
+    e.ports[0].postMessage('FAILURE');
+  }
+};