[Mac] Don't crash when dragging and dropping bookmarks within a bookmarks folder.

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

 // 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.
 
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_controller.h"
 
 #include "base/mac/mac_util.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/bookmarks/bookmark_utils.h"
@@ skipping 1343 matching lines @@
   // possible that a cancelPreviousPerformRequestsWithTarget: reduces
   // the refcount to 0, releasing us.  That's a bad thing to do while
   // this object (or others it may own) is in the event chain.  Thus
   // we have a retain/autorelease.
   [self retain];
   [NSObject cancelPreviousPerformRequestsWithTarget:self];
   [self autorelease];
 }
 
 - (NSWindow*)browserWindow {
-  return [parentController_ browserWindow];
+  return [barController_ browserWindow];
 }
 
 - (BOOL)canDragBookmarkButtonToTrash:(BookmarkButton*)button {
   return [barController_ canEditBookmarks] &&
          [barController_ canEditBookmark:[button bookmarkNode]];
 }
 
 - (void)didDragBookmarkToTrash:(BookmarkButton*)button {
   [barController_ didDragBookmarkToTrash:button];
 }
@@ skipping 610 matching lines @@
 
 - (void)setIgnoreAnimations:(BOOL)ignore {
   ignoreAnimations_ = ignore;
 }
 
 - (BookmarkButton*)buttonThatMouseIsIn {
   return buttonThatMouseIsIn_;
 }
 
 @end  // BookmarkBarFolderController