Download shelf autohides on showing in shell, just same as regular open

chrome/browser/ui/cocoa/download/download_shelf_controller.h

 // 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #import "chrome/browser/ui/cocoa/view_resizer.h"
 #include "ui/base/cocoa/tracking_area.h"
@@ skipping 102 matching lines @@
 
 // Similar to addDownloadItem above, but adds a DownloadItemController.
 - (void)add:(DownloadItemController*)download;
 
 // Remove a download, possibly via clearing browser data.
 - (void)remove:(DownloadItemController*)download;
 
 // Called by individual item controllers when their downloads are opened.
 - (void)downloadWasOpened:(DownloadItemController*)download;
 
+// Called by individual item controllers when their downloads are shown.
+- (void)downloadWasShown:(DownloadItemController*)download;
+
 // Notification that the download shelf is going to be destroyed and should
 // release the downloads.
 - (void)exiting;
 
 // Return the height of the download shelf.
 - (float)height;
 
 // Re-layouts all download items based on their current state.
 - (void)layoutItems;
 
 @end