Cocoa: Retain extension overflow menu item when readding

Bug: 866748
Change-Id: If48fa3bf307e8dc7876360840acced8e83f7572a
Reviewed-on: https://chromium-review.googlesource.com/1148015Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577522}

chrome/browser/ui/cocoa/app_menu/app_menu_controller.mm

@@ -367,6 +367,9 @@ class ToolbarActionsBarObserverHelper : public ToolbarActionsBarObserver {
     return;
 
   // Remove and re-add menu item so menu gets the correct size.
+  // |removeItemAtIndex:| can trigger an eager dealloc, so retain it
+  // in the meantime.
+  base::scoped_nsobject<NSMenuItem> menuItem([browserActionsMenuItem_ retain]);
   NSInteger index = [[self menu] indexOfItem:browserActionsMenuItem_];
   [[self menu] removeItemAtIndex:index];
   [[self menu] insertItem:browserActionsMenuItem_ atIndex:index];