Added default implementations of GetAcceleratorForCommandId.

ui/message_center/message_center_tray.cc

Index: ui/message_center/message_center_tray.cc
diff --git a/ui/message_center/message_center_tray.cc b/ui/message_center/message_center_tray.cc
index 246054e68d496c3d10b40ccc56c20504579afc36..7ce74a2b6487f02781334f4a2029b51b40cd4774 100644
--- a/ui/message_center/message_center_tray.cc
+++ b/ui/message_center/message_center_tray.cc
@@ -40,8 +40,6 @@ class NotificationMenuModel : public ui::SimpleMenuModel,
   // Overridden from ui::SimpleMenuModel::Delegate:
   bool IsCommandIdChecked(int command_id) const override;
   bool IsCommandIdEnabled(int command_id) const override;
-  bool GetAcceleratorForCommandId(int command_id,
-                                  ui::Accelerator* accelerator) const override;
   void ExecuteCommand(int command_id, int event_flags) override;
 
  private:
@@ -81,12 +79,6 @@ bool NotificationMenuModel::IsCommandIdEnabled(int command_id) const {
   return tray_->delegate()->IsContextMenuEnabled();
 }
 
-bool NotificationMenuModel::GetAcceleratorForCommandId(
-    int command_id,
-    ui::Accelerator* accelerator) const {
-  return false;
-}
-
 void NotificationMenuModel::ExecuteCommand(int command_id, int event_flags) {
   switch (command_id) {
     case kTogglePermissionCommand: