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 <memory>
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/has_weak_browser_pointer.h"
@@ skipping 102 matching lines @@
 // Add a new download item to the leftmost position of the download shelf. The
 // item should not have been already added to this shelf.
 - (void)addDownloadItem:(content::DownloadItem*)downloadItem;
 
 // 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 opened or
+// shown.
+- (void)downloadWasOpenedOrShown:(DownloadItemController*)download;
 
 // Return the height of the download shelf.
 - (float)height;
 
 // Re-layouts all download items based on their current state.
 - (void)layoutItems;
 
 @end