Added default implementations of GetAcceleratorForCommandId.

ui/base/models/simple_menu_model.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_BASE_MODELS_SIMPLE_MENU_MODEL_H_
 #define UI_BASE_MODELS_SIMPLE_MENU_MODEL_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 18 matching lines @@
   class UI_BASE_EXPORT Delegate {
    public:
     virtual ~Delegate() {}
 
     // Methods for determining the state of specific command ids.
     virtual bool IsCommandIdChecked(int command_id) const = 0;
     virtual bool IsCommandIdEnabled(int command_id) const = 0;
     virtual bool IsCommandIdVisible(int command_id) const;
 
     // Gets the accelerator for the specified command id. Returns true if the
-    // command id has a valid accelerator, false otherwise.
-    virtual bool GetAcceleratorForCommandId(
-        int command_id,
-        ui::Accelerator* accelerator) const = 0;
+    // command id has a valid accelerator, false otherwise. By default, returns
+    // false for all commands.
+    virtual bool GetAcceleratorForCommandId(int command_id,
+                                            ui::Accelerator* accelerator) const;
 
     // Some command ids have labels, sublabels, minor text and icons that change
     // over time.
     virtual bool IsItemForCommandIdDynamic(int command_id) const;
     virtual base::string16 GetLabelForCommandId(int command_id) const;
     virtual base::string16 GetSublabelForCommandId(int command_id) const;
     virtual base::string16 GetMinorTextForCommandId(int command_id) const;
     // Gets the icon for the item with the specified id, returning true if there
     // is an icon, false otherwise.
     virtual bool GetIconForCommandId(int command_id,
@@ skipping 141 matching lines @@
   MenuModelDelegate* menu_model_delegate_;
 
   base::WeakPtrFactory<SimpleMenuModel> method_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleMenuModel);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_MODELS_SIMPLE_MENU_MODEL_H_