[Mac] Integrate divider into browser-action overflow chevron.

chrome/browser/cocoa/extensions/chevron_menu_button.mm

Index: chrome/browser/cocoa/extensions/chevron_menu_button.mm
diff --git a/chrome/browser/cocoa/extensions/chevron_menu_button.mm b/chrome/browser/cocoa/extensions/chevron_menu_button.mm
new file mode 100644
index 0000000000000000000000000000000000000000..37159ae4bc04d87dca7ae5306de1b1b9181ee05c
--- /dev/null
+++ b/chrome/browser/cocoa/extensions/chevron_menu_button.mm
@@ -0,0 +1,15 @@
+// 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.
+
+#include "chrome/browser/cocoa/extensions/chevron_menu_button.h"
+
+#include "chrome/browser/cocoa/extensions/chevron_menu_button_cell.h"
+
+@implementation ChevronMenuButton
+
++ (Class)cellClass {
+  return [ChevronMenuButtonCell class];
+}
+
+@end