AcceleratorProvider: Make GetAcceleratorForCommandId const.

ash/common/system/web_notification/web_notification_tray.cc

 // 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.
 
 #include "ash/common/system/web_notification/web_notification_tray.h"
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
@@ skipping 432 matching lines @@
     return false;
   return message_center()->IsQuietMode();
 }
 
 bool WebNotificationTray::IsCommandIdEnabled(int command_id) const {
   return true;
 }
 
 bool WebNotificationTray::GetAcceleratorForCommandId(
     int command_id,
-    ui::Accelerator* accelerator) {
+    ui::Accelerator* accelerator) const {
   return false;
 }
 
 void WebNotificationTray::ExecuteCommand(int command_id, int event_flags) {
   if (command_id == kToggleQuietMode) {
     bool in_quiet_mode = message_center()->IsQuietMode();
     message_center()->SetQuietMode(!in_quiet_mode);
     return;
   }
   base::TimeDelta expires_in = command_id == kEnableQuietModeDay
@@ skipping 66 matching lines @@
 
 message_center::MessageCenterBubble*
 WebNotificationTray::GetMessageCenterBubbleForTest() {
   if (!message_center_bubble())
     return NULL;
   return static_cast<message_center::MessageCenterBubble*>(
       message_center_bubble()->bubble());
 }
 
 }  // namespace ash