AcceleratorProvider: Make GetAcceleratorForCommandId const.

chrome/browser/media_galleries/media_gallery_context_menu.cc

 // Copyright 2014 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/media_galleries/media_gallery_context_menu.h"
 #include "chrome/grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/models/menu_model.h"
 
 MediaGalleryContextMenu::MediaGalleryContextMenu(
@@ skipping 12 matching lines @@
 
 bool MediaGalleryContextMenu::IsCommandIdEnabled(int command_id) const {
   return true;
 }
 
 bool MediaGalleryContextMenu::IsCommandIdVisible(int command_id) const {
   return true;
 }
 
 bool MediaGalleryContextMenu::GetAcceleratorForCommandId(
-    int command_id, ui::Accelerator* accelerator) {
+    int command_id,
+    ui::Accelerator* accelerator) const {
   return false;
 }
 
 void MediaGalleryContextMenu::ExecuteCommand(int command_id, int event_flags) {
   callback_.Run(pref_id_);
 }