Add always-on-top property to app windows

chrome/test/data/extensions/platform_apps/windows_api_always_on_top/background.js

+// Copyright 2013 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.
+
+var callbackPass = chrome.test.callbackPass;
+
+function testAlwaysOnTop(testId, initValue, setOption) {
+  var options = { id: testId };
+  if (setOption)
+    options.alwaysOnTop = initValue;
+
+  chrome.app.window.create('index.html',
+                           options,
+                           callbackPass(function(win) {
+    // Check that isAlwaysOnTop() returns the initial value.
+    chrome.test.assertEq(initValue, win.isAlwaysOnTop());
+
+    // Toggle the current value.
+    // TODO(tmdiep): The new value of isAlwaysOnTop() should be checked
+    // asynchronously, but we need a non-flaky way to do this.
+    win.setAlwaysOnTop(!initValue);
+
+    win.contentWindow.close();
+  }));
+}
+
+chrome.app.runtime.onLaunched.addListener(function() {
+  chrome.test.runTests([
+
+    // Window is created with always on top enabled.
+    function testAlwaysOnTopInitTrue() {
+      testAlwaysOnTop('testAlwaysOnTopInitTrue', true, true);
+    },
+
+    // Window is created with always on top explicitly disabled.
+    function testAlwaysOnTopInitFalse() {
+      testAlwaysOnTop('testAlwaysOnTopInitFalse', false, true);
+    },
+
+    // Window is created with option not explicitly set.
+    function testAlwaysOnTopNoInit() {
+      testAlwaysOnTop('testAlwaysOnTopNoInit', false, false);
+    }
+
+  ]);
+});