Add reference to -webkit-app-region CSS style for no-frame windows.

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.
 
 // Use the <code>chrome.app.window</code> API to create windows. Windows
 // have an optional frame with title bar and size controls. They are not
 // associated with any Chrome browser windows.
 namespace app.window {
   dictionary Bounds {
     long? left;
@@ skipping 51 matching lines @@
 
     // Maximum width for the lifetime of the window.
     long? maxWidth;
 
     // Maximum height for the lifetime of the window.
     long? maxHeight;
 
     // Type of window to create.
     [nodoc] WindowType? type;
 
-    // Frame type: 'none' or 'chrome' (defaults to 'chrome').
+    // Frame type: 'none' or 'chrome' (defaults to 'chrome'). For 'none',
+    // the -webkit-app-region CSS property can be used to apply draggability

[scheib, 2013/09/15 04:35:15]

.
This appears to be the only place we will have this style documented, so please
add a bit more text here to make its usage clear. e.g. add:

"""
"-webkit-app-region: drag" can be used to mark regions draggable. "no-drag" can
be used to disable this style on nested elements.
"""

[Greg Billock, 2013/09/16 17:47:19]

Yeah, I was talking to a developer who found this hard to find. Adding your
additional explanation.

+    // to the app's window.
     DOMString? frame;
 
     // Size and position of the content in the window (excluding the titlebar).
     // If an id is also specified and a window with a matching id has been shown
     // before, the remembered bounds of the window will be used instead.
     Bounds? bounds;
 
     // Enable window background transparency.
     // Only supported in ash. Requires experimental API permission.
     boolean? transparentBackground;
@@ skipping 132 matching lines @@
     // Fired when the window is maximized.
     [nocompile] static void onMaximized();
 
     // Fired when the window is minimized.
     [nocompile] static void onMinimized();
 
     // Fired when the window is restored from being minimized or maximized.
     [nocompile] static void onRestored();
   };
 };