Try to fix top crasher....

chrome/browser/cocoa/bookmark_button_cell.mm

 // Copyright (c) 2010 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/cocoa/bookmark_button_cell.h"
 
 #include "app/l10n_util_mac.h"
 #include "base/logging.h"
 #include "base/nsimage_cache_mac.h"
 #include "base/sys_string_conversions.h"
@@ skipping 162 matching lines @@
   NSButton* button = static_cast<NSButton*>([self controlView]);
   if (button) {
     DCHECK([button isKindOfClass:[NSButton class]]);
     [button setAttributedTitle:ats.get()];
   }
 }
 
 // To implement "hover open a bookmark button to open the folder"
 // which feels like menus, we override NSButtonCell's mouseEntered:
 // and mouseExited:, then and pass them along to our owning control.
+// Note: as verified in a debugger, mouseEntered: does NOT increase
+// the retainCount of the cell or its owning control.
 - (void)mouseEntered:(NSEvent*)event {
   [super mouseEntered:event];
   [[self controlView] mouseEntered:event];
 }
 
 // See comment above mouseEntered:, above.
 - (void)mouseExited:(NSEvent*)event {
+  [[self controlView] mouseExited:event];
   [super mouseExited:event];
-  [[self controlView] mouseExited:event];
 }
 
 - (void)setDrawFolderArrow:(BOOL)draw {
   drawFolderArrow_ = draw;
   if (draw && !arrowImage_) {
     arrowImage_.reset([nsimage_cache::ImageNamed(@"menu_hierarchy_arrow.pdf")
                                     retain]);
   }
 }
 
@@ skipping 26 matching lines @@
                                    (NSHeight(imageRect) / 2.0));
     [arrowImage_ drawInRect:drawRect
                     fromRect:imageRect
                    operation:NSCompositeSourceOver
                     fraction:[self isEnabled] ? 1.0 : 0.5
                 neverFlipped:YES];
   }
 }
 
 @end