Context menu on views must show on mouse down for non-WIN.

ui/views/controls/menu/menu_controller.h

 // Copyright (c) 2012 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 UI_VIEWS_CONTROLS_MENU_MENU_CONTROLLER_H_
 #define UI_VIEWS_CONTROLS_MENU_MENU_CONTROLLER_H_
 
 #include "build/build_config.h"
 
 #include <list>
@@ skipping 549 matching lines @@
 
   // How deep we are in nested message loops. This should be at most 2 (when
   // showing a context menu from a menu).
   int message_loop_depth_;
 
   views::MenuConfig menu_config_;
 
   // The timestamp of the event which closed the menu - or 0 otherwise.
   base::TimeDelta closing_event_time_;
 
+  // Time when the menu is first shown.
+  base::TimeTicks menu_start_time_;
+
   DISALLOW_COPY_AND_ASSIGN(MenuController);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_MENU_MENU_CONTROLLER_H_