[Extensions] Don't run unload listeners when an extension is removed

chrome/test/data/extensions/unload_listener/page.js

Index: chrome/test/data/extensions/unload_listener/page.js
diff --git a/chrome/test/data/extensions/unload_listener/page.js b/chrome/test/data/extensions/unload_listener/page.js
new file mode 100644
index 0000000000000000000000000000000000000000..205375e6711c40f612a0622abdf4cbf0619f7a79
--- /dev/null
+++ b/chrome/test/data/extensions/unload_listener/page.js
@@ -0,0 +1,12 @@
+// 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.
+
+function onUnload() {
+  var xhr = new XMLHttpRequest();
+  xhr.open('GET', 'https://www.example.com/', true);
+  xhr.send();
+}
+
+window.onbeforeunload = onUnload;
+window.onunload = onUnload;