Transparent apps support

chrome/common/extensions/api/app_window.idl

 // 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.
 
 namespace app.window {
   dictionary CreateWindowOptions {
     // Id to identify the window. This will be used to remember the size
     // and position of the window and restore that geometry when a window
     // with the same id (and no explicit size or position) is later opened.
     DOMString? id;
@@ skipping 30 matching lines @@
 
     // Maximum width of the window.
     long? maxWidth;
 
     // Maximum height of the window.
     long? maxHeight;
 
     // Window type: 'shell' (the default) is the only currently supported value.
     DOMString? type;
 
-    // Frame type: 'none' or 'chrome' (defaults to 'chrome').
+    // EXPERIMENTAL: Frame type: 'none' or 'chrome' (defaults to 'chrome').

[Mihai Parparita -not on Chrome, 2012/09/28 19:15:34]

This isn't an experimental option.

[Bernie, 2012/10/10 21:05:01]

What I meant to say is that this option requires the experimental API permission
(now fixed).

     DOMString? frame;
+
+    // EXPERIMENTAL: Enable window background transparency.
+    boolean? transparentBackground;

[jeremya, 2012/10/04 22:12:56]

Can you add that it's only supported on ash?

[Bernie, 2012/10/10 21:05:01]

Done.

   };
 
   callback CreateWindowCallback =
       void ([instanceOf=AppWindow] object created_window);
 
   dictionary AppWindow {
     // Focus the window.
     static void focus();
 
     // Minimize the window.
@@ skipping 42 matching lines @@
     // If you specify both a regular and a default value for the same option
     // the regular value is the only one that takes effect.
     static void create(DOMString url,
                        optional CreateWindowOptions options,
                        optional CreateWindowCallback callback);
 
     [nocompile] static AppWindow current();
     [nocompile, nodoc] static void initializeAppWindow(object state);
   };
 };