Add always-on-top property to app windows

chrome/renderer/resources/extensions/app_window_custom_bindings.js

 // Copyright (c) 2012 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.
 
 // Custom binding for the app_window API.
 
 var appWindowNatives = requireNative('app_window_natives');
 var Binding = require('binding').Binding;
 var Event = require('event_bindings').Event;
 var forEach = require('utils').forEach;
@@ skipping 94 matching lines @@
     };
     AppWindow.prototype.isFullscreen = function() {
       return appWindowData.fullscreen;
     };
     AppWindow.prototype.isMinimized = function() {
       return appWindowData.minimized;
     };
     AppWindow.prototype.isMaximized = function() {
       return appWindowData.maximized;
     };
+    AppWindow.prototype.isAlwaysOnTop = function() {
+      return appWindowData.alwaysOnTop;
+    };
 
     Object.defineProperty(AppWindow.prototype, 'id', {get: function() {
       return appWindowData.id;
     }});
 
     appWindowData = {
       id: params.id || '',
       bounds: { left: params.bounds.left, top: params.bounds.top,
                 width: params.bounds.width, height: params.bounds.height },
       fullscreen: params.fullscreen,
       minimized: params.minimized,
-      maximized: params.maximized
+      maximized: params.maximized,
+      alwaysOnTop: params.alwaysOnTop
     };
     currentAppWindow = new AppWindow;
   });
 });
 
 function boundsEqual(bounds1, bounds2) {
   if (!bounds1 || !bounds2)
     return false;
   return (bounds1.left == bounds2.left && bounds1.top == bounds2.top &&
           bounds1.width == bounds2.width && bounds1.height == bounds2.height);
@@ skipping 37 matching lines @@
 
 function onAppWindowClosed() {
   if (!currentAppWindow)
     return;
   dispatchEventIfExists(currentAppWindow, "onClosed");
 }
 
 exports.binding = appWindow.generate();
 exports.onAppWindowClosed = onAppWindowClosed;
 exports.updateAppWindowProperties = updateAppWindowProperties;