Updating JSON Schema Compiler to add description field to schemas.

chrome/common/extensions/api/experimental_media_galleries.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.
 
+// An experimental API that expands upon the <code>chrome.mediaGalleries</code>
+// API's functionality.
 namespace experimental.mediaGalleries {
 
   callback AssembleMediaFileCallback =
       void ([instanceOf=Blob] optional object mediaFile);
 
   interface Functions {
     // Create a new MediaFile setting the metadata in the Blob to the supplied
     // values, overriding any existing metadata in the media file. If user agent
     // does not recognize the Blob as a supported file format, it will fail.
     // |mediaFileContents| : the media bytes.
     // |metadata| : the metadata. TODO(estade): this should be
     // [instanceOf=Metafile].
     static void assembleMediaFile(
         [instanceOf=Blob] object mediaFileContents,
         object metadata,
         AssembleMediaFileCallback callback);
 
     // Get any thumbnails contained in the passed media file. The resulting
     // directory reader refers to a virtual directory that can not be navigated
     // to. If there are no thumbnails in the passed file entry, the virtual
     // directory will have no entries.
     // TODO(estade): The return type should be Directory. The argument type
     // should be [instanceOf=FileEntry].
     [nocompile] static object extractEmbeddedThumbnails(object mediaFile);
   };
 
 };