RenderWidget popup should be a NSWindow so it can go outside the main window.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_controller.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_CONTROLLER_H_
 #define CHROME_BROWSER_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_nsobject.h"
@@ skipping 12 matching lines @@
 @interface BookmarkBarFolderController :
     NSWindowController<BookmarkButtonDelegate,
                        BookmarkButtonControllerProtocol,
                        NSUserInterfaceValidations> {
  @private
   // The button whose click opened us.
   scoped_nsobject<BookmarkButton> parentButton_;
 
   // Bookmark bar folder controller chains are torn down in two ways:
   // 1. Clicking "outside" the folder (see use of
-  // CrApplicationEventHookProtocol in the bookmark bar controller).
+  // CrEventHookProtocol in the bookmark bar controller).
   // 2. Engaging a different folder (via hover over or explicit click).
   //
   // In either case, the BookmarkButtonControllerProtocol method
   // closeAllBookmarkFolders gets called.  For bookmark bar folder
   // controllers, this is passed up the chain so we begin with a top
   // level "close".
   // When any bookmark folder window closes, it necessarily tells
   // subcontroller windows to close (down the chain), and autoreleases
   // the controller.  (Must autorelease since the controller can still
   // get delegate events such as windowDidClose).
@@ skipping 178 matching lines @@
 - (BOOL)canScrollDown;
 - (CGFloat)verticalScrollArrowHeight;
 - (NSView*)visibleView;
 - (NSScrollView*)scrollView;
 - (NSView*)folderView;
 
 - (BookmarkButton*)buttonForDroppingOnAtPoint:(NSPoint)point;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_BOOKMARKS_BOOKMARK_BAR_FOLDER_CONTROLLER_H_