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').
+    // Frame type: 'none', 'chrome' (default), 'experimental-html'.
+    // The value 'experimental-html' requires experimental API permission.

[jeremya, 2012/11/11 23:22:43]

I'd rather we don't document the 'experimental-html' option here.

[Bernie, 2012/12/18 21:08:36]

Ok, reverted this chunk.

     DOMString? frame;
 
+    // Enable window background transparency.
+    // Only supported in ash. Requires experimental API permission.
+    boolean? transparentBackground;
+
     // If true, the window will be created in a hidden state. Call show() on
     // the window to show it once it has been created. Defaults to false.
     boolean? hidden;
   };
 
   callback CreateWindowCallback =
       void ([instanceOf=AppWindow] object created_window);
 
   dictionary Bounds {
     long? left;
@@ skipping 71 matching lines @@
                        optional CreateWindowCallback callback);
 
     // Returns an <a href="#type-AppWindow">AppWindow</a> object for the
     // current script context (ie JavaScript 'window' object). This can also be
     // called on a handle to a script context for another page, for example:
     // otherWindow.chrome.app.window.current().
     [nocompile] static AppWindow current();
     [nocompile, nodoc] static void initializeAppWindow(object state);
   };
 };