Added "Look Up in Dictionary" item to context menu for Mac.

chrome/browser/tab_contents/render_view_context_menu.h

 // 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.
 
 #ifndef CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_CONTEXT_MENU_H_
 #define CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_CONTEXT_MENU_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 38 matching lines @@
   virtual void ExecuteCommand(int command_id);
 
  protected:
   void InitMenu();
 
   // Platform specific functions.
   virtual void PlatformInit() = 0;
   virtual bool GetAcceleratorForCommandId(
       int command_id,
       menus::Accelerator* accelerator) = 0;
+  virtual void LookUpInDictionary();
 
   // Attempts to get an ExtensionMenuItem given the id of a context menu item.
   ExtensionMenuItem* GetExtensionMenuItem(int id) const;
 
   ContextMenuParams params_;
   TabContents* source_tab_contents_;
   Profile* profile_;
 
   menus::SimpleMenuModel menu_model_;
 
@@ skipping 67 matching lines @@
   GURL selection_navigation_url_;
 
   menus::SimpleMenuModel spellcheck_submenu_model_;
   menus::SimpleMenuModel bidi_submenu_model_;
   ScopedVector<menus::SimpleMenuModel> extension_menu_models_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewContextMenu);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_RENDER_VIEW_CONTEXT_MENU_H_