Move chrome.downloads out of experimental to dev

chrome/common/extensions/api/experimental_serial.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.
 
-// File-level comment to appease parser. Eventually this will not be necessary.
-
 [nodoc] namespace experimental.serial {
 
   callback GetPortsCallback = void (DOMString[] ports);
 
   dictionary OpenInfo {
     // The id of the opened connection.
     long connectionId;
   };
 
   callback OpenCallback = void (OpenInfo openInfo);
@@ skipping 46 matching lines @@
     // Writes a string to the given connection.
     // |connectionId| : The id of the connection.
     // |data| : The string to write.
     // |callback| : Called when the string has been written.
     static void write(long connectionId,
                       ArrayBuffer data,
                       WriteCallback callback);
   };
 
 };